Edward Snowden, the U.S. intelligence leaker who was granted asylum in Russia, contacted Russian officials before he flew to Moscow and spent several days at the country's diplomatic mission in Hong Kong, a newspaper said on Monday.

Kommersant, citing several informed sources, also said the former U.S. National Security Agency contractor did not board a flight to Cuba from Moscow as planned because under pressure from Washington, Havana said it would not allow the plane to land.

Russian Foreign Minister Sergei Lavrov has warned U.S. Secretary of State John Kerry over the "extremely dangerous consequences" of launching military action against the Syrian regime, the foreign ministry said Monday.

Lavrov told Kerry in a telephone call Sunday that Moscow was "deeply alarmed" by comments from U.S. officials indicating a readiness to intervene in Syria in the wake of accusations the regime had used chemical weapons, it said in a statement.

Russian police on Sunday briefly detained top Kremlin critic Alexei Navalny after a campaign rally for the Moscow mayoral election he is contesting next month, police said.

Violations of the law on mass protests were at issue, the police said in a statement about half an hour after taking the opposition leader away in a van following a rally for the September 8 vote.

Military action against the Syrian regime would be a "tragic mistake", Russia said Sunday, warning the West not to preempt the results of a U.N. probe into alleged deadly chemical attacks.

Moscow warned there was a danger of history repeating itself a decade after the U.S.-led invasion of Iraq, which it opposed, and urged the United States to refrain from any reckless decision.

President Barack Obama is moving the United States closer to an "illegitimate" war in Syria, raising echoes of predecessor George W. Bush's moves before invading Iraq, a prominent Russian lawmaker said Sunday.

"Inescapably, Obama is moving towards war in Syria just like Bush was towards war in Iraq," Alexei Pushkov, the head of the Russian lower house of parliament's international committee, said on Twitter.

German Chancellor Angela Merkel has criticized Damascus allies China and Russia for blocking a Western-backed U.N. text demanding that inspectors probing chemical weapons use in Syria be given unfettered access.

Her comments were made in an interview with Focus magazine, extracts of which were published on Saturday, even as a top U.N. envoy arrived in Damascus to discuss the terms on an inquiry into the alleged chemical attacks.

Russia hit out Friday at calls for force to be used after Syria's opposition and European states accused the war-torn country's regime of killing hundreds in chemical weapons attacks.

As the regime's international allies and foes traded barbs over the reported atrocity, U.S. President Barack Obama said the alleged use of chemical weapons was "clearly a big event of grave concern".

Russia on Friday said it had told the Syrian government to cooperate with U.N. experts after reports of a deadly chemical weapons attack outside Damascus, adding it was now up to rebels to allow access to the area.

Foreign Minister Sergei Lavrov told U.S. counterpart John Kerry in a phone call that immediately after the reports first emerged the "Russian side called on the Syrian government to cooperate with the U.N. chemical experts," the foreign ministry said in a statement.

Russians in the Far East on Friday scrambled to contain record floods which have affected more than 50,000 people and threatened to paralyze one of the region's biggest cities.

Heavy rains pounding the Far East over the past weeks swelled local rivers, with floodwaters wreaking havoc in Khabarovsk, a city of nearly 600,000 that sits at the confluence of the Amur and Ussury rivers near a Chinese border.

Russia said Thursday that a U.N. weapons inspection team in Syria must get the government's approval to visit the site of an alleged chemical attack near Damascus that the opposition says killed hundreds.

The Russian foreign ministry's official spokesman said the site of Wednesday's incident was controlled by rebels and that security concerns must also be addressed before any U.N. inspections are made.