Despite Russia's strong reaction, British Prime Minister Gordon Brown was not in the least defensive about Britain's decision to expel four Russian diplomats on Monday.
"We have no apologies for the action we have taken," Brown said.
"I hope it is understood in other parts of the world that we are not prepared to allow a situation of lawlessness to develop in London as a result of a failure to act."
Brown, who is visiting Berlin, said he wanted a good relationship with Russia, but added:"When a murder takes place... and an independent prosecuting authority makes it absolutely clear what is in the interests of justice - and there is no forthcoming co-operation - then action has to be taken."
David Miliband, Foreign Secretary, also told the House of Commons that a "significant body of evidence" implicated Lugovoi in the "horrifying and lingering death" of Litvinenko from radiation poisoning. He added that Britain had no choice but to send a "clear and proportionate signal" to Moscow.