There is a strong possibility of terror attacks around the Sochi Winter Olympics, a Whitehall source has told ITV News. The threat level of an attack before or during the games is substantial, they added.
Terrorist attacks in Russia are "very likely to occur" before or during the Winter Olympics in Sochi, UK officials have warned.
The Winter Olympics will begin next week with 88 countries due to compete.
A document examining the level of risk, seen by the BBC, claims the Caucasus group Imarat Kavkaz (IK) poses the main danger, although it does question whether the group has the capability to attack the event within the timeframe.
The report suggests that Sochi would be far more difficult to attack due to the huge security presence in the host city.
Security has heavily increased in Russia since a twin attack on the city of Volgograd in December which killed 34 people last month.
Video of a terrifying raid by the Russian security services on suspected Islamist militants has been released by the authorities.
For years Dagestan has been the scene of a separatist struggle. Now it is home to Islamist militants who have vowed to target the Games.