The United States warned American and foreign airlines on Wednesday that terrorists could try to place explosives disguised as toothpaste on Russia-bound flights, AFP reports.
An official told the news agency the U.S. has information "specifically targeting flights to Russia," where the Winter Olympics will begin in the resort city of Sochi on Friday.
In a statement, the Department of Homeland Security said that "out of an abundance of caution," it regularly shares relevant information with partners both at home and abroad.
"While we are not aware of a specific threat to the homeland at this time, this routine communication is an important part of our commitment to making sure we meet that priority," it said, according to AFP.
"As always, our security apparatus includes a number of measures, both seen and unseen, and DHS will continue to adjust security measures to fit an ever evolving threat environment," it said.
Security at the February 7-23 Games has been a major concern for Washington following two deadly December suicide attacks in the southern Russian city of Volgograd.
The first bombing, on December 29, took place at a train station in the city, killing 18 people.
A day later, a suicide bombing on a trolleybus in the same city killed another 16 people.
Terrorists believed to be involved in the Volgograd bombings have threatened to attack the Olympics.
In a video posted on a well-known jihadi forum last month, the terrorists promised Russian President Vladimir Putin that he will receive “a present from us for the Muslim blood that's been spilled.”
Adding to the concern is a stream of threats from Islamist militants in the volatile northern Caucasus region, reported AFP.
Earlier Wednesday, officials said two U.S. warships have arrived in the Black Sea and will stand ready to offer assistance in the case of a security emergency at the massive sports event.
Recent reports said Russia was trying to hunt down three potential suicide bombers, all female Muslims, who are suspected of planning to carry out attacks during the upcoming Olympics.
The three women are all the wives of killed terrorists, and are pictured wearing traditional Muslim head coverings in police fliers posted in Sochi.