ANTIQUES SHOPS

On Facebook and Twitter, activists called for a big turnout at "The March of the Millions", the first major protest since Putin was sworn in on May 7, a day after police searched the homes of opposition leaders in raids Kremlin critics said were reminiscent of methods used by Soviet dictator Josef Stalin.

"Everyone in Moscow! If you don't want to live in a dictatorship, like we did before, then (come to the rally)," Twitter user Lyapis Trubetskoy posted. On Facebook, more than 6,500 people said they would attend.

The protest will begin without top opposition leaders who were summoned to appear before federal investigators just before the start of the march and rally to face questions over violence at a protest on the eve of Putin's inauguration.

"The questioning is a stupid formality aimed exclusively at preventing us from speaking at the demonstration," Alexei Navalny, an anti-corruption blogger and vocal Putin critic, said before entering the federal Investigative Committee building.

A lawyer for leftist leader Sergei Udaltsov said his client would ignore the summons and attend the rally instead.

After tolerating the biggest protests of his 12-year rule while seeking election, the searches and summonses signal a harsher approach to dissent at the start of the former KGB officer Putin's new term as president.

On Friday, he signed a law increasing fines, in some cases more than 100-fold, for violations of public order at demonstrations, despite warnings from his human rights council that it was an unconstitutional infringement on free assembly.

Law enforcement officers delivered the summonses during searches of the homes of leaders including Navalny, Udaltsov and socialite Ksenia Sobchak on Monday.

Police and investigators raided their Moscow apartments on a sleepy morning in the middle of a three-day weekend, seizing computer drives and discs, photographs and other belongings as armed guards stood outside.

"People barged in at 8 a.m., gave me no chance to get dressed, robbed the apartment, humiliated me," Sobchak said in a Twitter post. "I never thought we would return to such repression in this country."

"They rifled through everything, every wardrobe, in the toilet, in the refrigerator. They searched under the beds," Udaltsov, who was summoned for questioning along with his wife on Tuesday, told reporters of the search of their home.

Police left Navalny's apartment 13 hours after they entered, carrying boxes. Navalny emerged later and told reporters the summons was clearly aimed to keep him from the rally but vowed that he would attend.

In power since 2000, Putin won a third presidential term in March despite a series of protests that drew tens of thousands into the streets, angry over alleged fraud in a December parliamentary election won by his United Russia party.

Many protesters were middle-class city dwellers who have benefited from the oil-fuelled boom Russia has experienced during Putin's years at the helm but want more say in politics and fear his prolonged rule will bring economic stagnation.

"SCARE TACTICS"

Police largely left those earlier protests alone but began to crack down after Putin's election, beating protesters at the rally on May 6 and repeatedly dispersing groups trying to set up Occupy-style camps since then, briefly detaining hundreds.

They have detained 12 people over violence at the May 6 protest on charges punishable by more than a year in jail, and the latest summonses seemed to carry the implicit threat that opposition leaders could potentially face similar charges.

Monday's searches sparked a wave of angry comment.

"Vova is crazy," one Twitter user wrote, referring to Putin by the common nickname for Vladimir. Others messaged under the tag that translates as "hello1937" - a reference to the deadliest year of Stalin's repression.

"What we are witnessing today is in essence the year 1937," opposition activist Yevgenia Chirikova said at an emergency meeting in a cramped office to discuss plans for the protest. She said the searches and summonses were clearly a scare tactic.

Udaltsov predicted it would backfire.

"Some people may get scared, but people are less frightened now" following the winter protests, he told reporters. "They are more active, and I think even more people will come than had initially planned to.

"They are digging themselves a pit - deeper and deeper."

(Writing by Steve Gutterman; editing by Elizabeth Piper)

In the latest sign Washington is working with other countries to pressure Iran's nuclear program, India, South Korea, Turkey and four more economies will receive waivers from financial sanctions in return for significantly cutting purchases of Iranian oil, Secretary of State Hillary Clinton said.

China, which alone buys as much as a fifth of Iran's crude exports, and Singapore, where much of the country's fuel oil is blended, did not receive such waivers, ramping up pressure on two important U.S. trade partners in Asia.

The sanctions, which the United States may impose starting on June 28, are Washington's most ambitious measures yet to strangle Iran's nuclear program by cutting funding from its oil export sales.

The United States and the European Union believe Iran is trying to build nuclear weapons. Tehran says the program is strictly for civilian purposes.

Beyond the 27-country EU, which has banned Iranian imports from July under separate sanctions, other buyers of Iran's crude have pledged to cut purchases by up to a fifth.

"By reducing Iran's oil sales, we are sending a decisive message to Iran's leaders: until they take concrete actions to satisfy the concerns of the international community, they will continue to face increasing isolation and pressure," Clinton said in a release.

She is hosting high-level, previously scheduled talks with ministers from India and South Korea, Iran's second- and fourth-largest oil buyers, this week in Washington.

Geng Shuang, a spokesman for the Chinese embassy in Washington, said his government "opposes unilateral sanctions imposed by one country on others". He added that China will push for a diplomatic solution to the Iran nuclear issue through negotiations.

South Africa, Taiwan, Malaysia and Sri Lanka will also be exempt from the sanctions, Clinton said. Japan and 10 EU countries had been granted exceptions in March.

RELIEF

Banks and other institutions in the economies that received waivers will be given a six-month break from the threat of being cut off from the U.S. financial system under sanctions signed late last year by President Barack Obama.

China, Japan, India and South Korea cut imports by about a fifth from the 1.45 million barrels per day they were buying a year ago as they prepared for the sanctions to come into effect.

The cuts and threat of sanctions have helped drain Iran's oil revenues by an estimated $10 billion since the start of the year, said Senator Robert Menendez, a Democrat who helped craft the measures.

"While I look forward to seeing the actual levels of reductions made by each country, I presume that they will be on par with the significant reductions in purchases made by Japan," which cut its buying by about 15 percent to 22 percent, he said.

Oil traders had largely expected the exemptions after the cuts, with Obama seeking to tread a fine line between tightening the screws on Tehran and triggering a squeeze on global oil supplies that could tip the U.S. economy back into recession.

"The White House doesn't want to see 1 million barrels per day (bpd) of Iranian exports cut when oil prices are still relatively high, but at the same time they want to make sure the sanctions still have some bite," said Andy Lebow, senior vice president of energy at Jefferies Bache in New York.

"No one thinks they're going to slap sanctions on China."

The bigger issue for markets will be whether separate European sanctions blocking access to tanker insurance cause shipments to grind to a halt from July 1.

CHINA TALKS

Although China did not immediately receive a waiver, it does not necessarily follow that the United States will impose sanctions on the country from June 28. A U.S. official said last week it would take some time for Washington to gather evidence to support punitive measures against banks that have processed oil transactions.

It was not immediately clear why the administration did not grant China an exemption. Backers of tough sanctions on Tehran believe China has received clandestine cargoes of oil from Iran, which has disabled tracking devices on some of its shipments.

Senior U.S. officials sidestepped questions about those issues in a conference call with reporters, but said the dialogue with China on the issue was constructive.

"We are in discussions with China. It would be premature to comment further on where those discussions might lead," a senior official said.

He said the United States continued to outline to China the requirements of U.S. law "and we are engaged in a good-faith dialogue to be able to work toward a solution that in our view addresses the fundamental point here, which is how do we reduce the volume of purchases of Iranian crude oil".

Bob McNally, head of the Washington-based oil consultancy Rapidan Group, said Obama may have delayed a decision on China to avoid criticism he is soft on Beijing ahead of the U.S. presidential election on November 6.

"I wouldn't be surprised to see China raked over the coals a little longer before a decision is taken on whether to grant them a waiver," he said.

Obama is under pressure from Congress, which may pass even tougher sanctions on Iran.

"If the administration is willing to exempt all of these countries, who will they make an example out of?" said U.S. Representative Ileana Ros-Lehtinen, a Republican and chairman of the House Foreign Affairs Committee.

(Additional reporting by Roberta Rampton, Paul Eckert and Andrew Quinn in Washington and David Sheppard in New York; Editing by Sandra Maler and Dale Hudson)