US says Russia is refusing to share details of terror threats against Sochi Olympics

Russia has refused to share specific information on terror threats made against the Sochi Olympics with Washington.

The revelation yesterday by a US official came amid mounting fears about security at the Winter Games.

The Obama administration has already publicly stopped short of expressing full confidence in the Russian security operation ahead of the sporting spectacular, which opens next month in the Black Sea resort.

Signs of increasing US concern followed a phone discussion on security at the Games between Presidents Barack Obama and Vladimir Putin on Tuesday.

A senior US official said on Wednesday that Russia "has not been forthcoming in sharing specific threat information".

Extremist insurgents based in North Caucasus republics such as Dagestan, who are seeking their own independent state, have vowed to disrupt the Games to undermine Putin.

Washington has sophisticated intelligence and anti-terrorism capabilities that have been deployed in previous Olympics.

And it has offered to help Russia as it places a ring of steel around the host city and its venues in preparation for welcoming thousands of spectators and athletes. White House spokesman Jay Carney admitted earlier that there was "concern" in Washington about an increase in reported threats by Islamic extremists relating to the Games.

He said the US would send diplomatic security and FBI agents who would liaise with Russian officials to protect American athletes and spectators.

But he did not express full confidence in Russia's preparations. "I wouldn't be qualified or wouldn't want to venture to assess overall," Carney said.

"These kinds of major events around the world obviously present security challenges," he said, without confirming whether Russia had accepted US offers of help. "The president spoke with President Putin about this. We have offered any assistance that they might want to avail themselves of."

At the State Department, deputy spokeswoman Marie Harf deflected a query as to whether the US had full confidence in the Russian effort.

But she added that Washington knew Moscow was "committed to doing everything they can in terms of security".

The careful public tone adopted by the administration could signal a desire to avoid offending or antagonising Russia in the run-up to the Games while concerns are expressed privately with top Russian officials.

The Games are seen as hugely important to Putin's personal prestige and to his project of restoring stability and honour to Russia as it emerges from the post-cold war period that saw the collapse of the Soviet Union.

Ties between Moscow and Washington are currently as tense as they have been for many years, with the case of fugitive US intelligence leader Edward Snowden - granted temporary asylum by Russia - and the Kremlin's support for Syrian President Bashar al-Assad causing friction.

The US and some European national teams received e-mailed threats of terrorist strikes on their athletes and supporters if they participate in Sochi.

But the International Olympic Committee said the anonymous warnings lacked credibility.

On Monday, the Pentagon said it was ready to deploy air and naval assets - including two ships - to help secure the Olympics, which begin on February 7.

Additional reporting by Reuters