The United States issued a warning last night to airports and to some airlines flying to Russia for the Olympics to watch for toothpaste tubes that could hold ingredients to make a bomb on a plane, a senior US security official said.
The official did not say whether any specific intelligence led to the warning, which was not issued to the public.
The US department of homeland security passed on the threat to airlines that have direct flights to Russia, including some that originate in the United States, according to a law enforcement official.
The official said the airlines were warned that explosive devices could be assembled in-flight or upon arrival at the Olympics.
The department said it “regularly shares information with domestic and international partners, including those associated with international events such as the Sochi Olympics”.
Delta Airlines is the only US carrier with a direct flight from the United States to Moscow. Russian airlines Aeroflot and Transaero both operate several non-stop flights from the US.
United Airlines, the official airline of the US Olympic team, does not have scheduled service to Russia but is operating some charter flights to Sochi.
Russian forces are on high alert to head off possible militant attacks at the Winter Olympic Games, which begin tomorrow in Sochi. Some US politicians have expressed concern about security at the Black Sea resort, but US president Barack Obama has said he believes Sochi is safe.
Suicide bombers killed 34 people in the Russian city of Volgograd, 400 miles (700 km) northeast of Sochi, in December. The attacks raised fears of violence at the Olympics.
US security officials said they were not aware of any specific threats to the United States now.
In 2009 a Nigerian man tried to set off an explosive hidden in his underwear aboard a US-bound airliner. In 2001 a man tried to blow up a jumbo jet with explosives in his shoes.
Agencies