Two Britons 'among Moscow victims'
Two British nationals are among more than 30 people killed by a suicide bomber at Moscow's busiest airport, according to Russian investigators.
A Foreign Office spokesman said he was aware of the reports but could not confirm the deaths.
He said: "We have a consular team on the ground and we are urgently investigating."
Russian investigative committee spokesman Vladimir Markin has not identified the British victims who died in the explosion at Domodedovo airport.
The blast saw more than 30 people killed and almost 170 injured.
David Cameron offered Britain's "complete support" in dealing with the terror attack in a telephone call with Mr Medvedev, Downing Street said.
"The Prime Minister utterly condemned today's explosion at Domodedovo airport. He offered his condolences and sympathies to all those who had been affected by what he described as an appalling attack," a Number 10 spokeswoman said.
"The Prime Minister assured President Medvedev of his complete support and said that the Russian authorities could count on Britain for any assistance they needed.
"The Prime Minister made clear that the people of Britain stood with the people of Russia in the face of these events and said that 'we should never allow the terrorists to win'."