A U.S. State Department team will visit Moscow this week to discuss the Syria crisis, a top official said Tuesday as Western pressure mounted on Russia to back new action against its Soviet-era ally.

"We are in the process of meeting (U.S. Secretary of State) Hillary Clinton's deputies who work on the Middle East and Syria in particular," Russia's Deputy Foreign Minister Mikhail Bogdanov told the RIA Novosti state news agency.

Russia on Saturday quietly marked half a century since Soviet forces brutally suppressed a rare protest led by striking factory workers in one of the worst massacres of the USSR's postwar era.

Twenty-six people were killed on June 2, 1962 when Soviet troops fired on the mass protest against working conditions and rising prices in the southern city of Novocherkassk.

Russia's foreign ministry on Friday blamed the Houla massacre, in which 108 people were killed, on foreign assistance to Syrian rebels, including arms deliveries and mercenary training.

"The tragedy in Houla showed what can be the outcome of financial aid and smuggling of modern weapons to rebels, recruitment of foreign mercenaries and flirting with various sorts of extremists," the ministry said in a statement.

Russia said on Wednesday that Iran was ready to hold serious talks on its nuclear program that could lead to a gradual lifting of sanctions in exchange for broader transparency from Tehran.

"We have a clear understanding... that Iran is ready to agree on concrete actions," Foreign Minister Sergei Lavrov told reporters, without elaborating.

There is still no agreement among leaders of the world's richest nations on the final text of a declaration that will touch upon the protracted conflict in Syria, a Kremlin advisor said Thursday.

The leaders of the G8 -- Britain, Canada, France, Germany, Italy, Japan, Russia, and the United States -- will meet Friday and Saturday for a summit at the Camp David presidential retreat near Washington.

Moscow authorities broke up a week-long Occupy protest on Wednesday that sprung up in response to President Vladimir Putin's inauguration, warning they would prevent similar actions during his third term.

The dawn-hours raid on dozens of sleeping protesters brought an abrupt end to younger Russians' first attempt to emulate the tent city tactic that is increasing popular in the West.

Newly-inaugurated President Vladimir Putin on Wednesday presided over Russia's annual display of military power as missiles and thousands of troops paraded across Red Square to mark World War II victory.

Two days after Putin's swearing-in, over 14,000 servicemen marched alongside nuclear-capable missiles to commemorate the 67th anniversary of the Soviet victory over Nazi Germany.

Moscow police on Tuesday detained two prominent leaders of the protest movement against newly-inaugurated President Vladimir Putin after they staged an unusual night-time sit-in close to the Kremlin.

Anti-corruption crusader Alexei Navalny and ultra-leftist Sergei Udaltsov were taken to a nearby police station where they were expected to be fined but later freed, their lawyer Nikolai Polozov wrote on Twitter.

Baton-wielding riot police roughly broke up a Moscow protest rally Sunday on the eve of Vladimir Putin's return for a third Kremlin term, arresting more than 400 people including top opposition leaders.

The clashes just over the river from the Kremlin were the most violent since the first rallies against the Russian strongman began in December and set an ominous tone ahead of his glitzy presidential inauguration ceremony Monday.

Russia said Thursday its dispute with the United States over missile defense was near a "dead end" and warned it might have to deploy new rockets in Europe to take out elements of the controversial shield.

"We have not been able to find mutually-acceptable solutions at this point and the situation is practically at a dead end," Defense Minister Anatoly Serdyukov told a televised conference on missile defense issues.