'Appropriate steps' taken on US Oly safety

US President Barack Obama has been assured that the United States is "taking all appropriate steps regarding the safety of Americans" at the upcoming Winter Olympics.

During a high-level briefing in the Situation Room, Obama directed his team to continue to work closely with the Russian government and "to review carefully and act on any new information that might affect the security of the Games."

Those attending the meeting included Vice President Joe Biden, US Secretary of State John Kerry and National Security Advisor Susan Rice, among other top officials, the White House said on Tuesday.

Security at the February 7-23 Games in the Russian resort city of Sochi has been a major concern for Washington following two deadly December suicide attacks in the southern city of Volgograd and a stream of threats from Islamist militants in the volatile northern Caucasus region.

"The president was briefed on the security environment, our cooperation with Russian authorities, and on the full range of US government support for our athletes, delegation, and Americans attending the Olympics," the White House said in a statement.

"He was assured by his team that they are taking all appropriate steps regarding the safety of Americans."

The White House has expressed concern about Russia's reluctance to share details of various security threats.

Also Tuesday, a top US counter-terrorism official warned that the biggest security threat facing the Olympics is a possible attack in areas outside of Sochi and its heavily-guarded venues.