US warns against toothpaste bombs on Russian flights as Games begin

The US government has warned American and foreign airlines that terrorists could try to hide explosives in toothpaste tubes on Russia-bound flights.

An official said it had information "specifically targeting flights to Russia", where the Winter Olympics will begin in the resort city of Sochi today.

The Department of Homeland Security said on Wednesday that, "out of an abundance of caution", it regularly shared 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.

"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."

US President Barack Obama's National Security Council said the disclosure had not affected existing guidelines about travel to Sochi. "If we should receive information in the coming days and weeks that changes our assessment of whether people should travel to Sochi, we will make that information public through the State Department's usual channels," spokeswoman Laura Magnuson said.