LONDON, July 10 (RIA Novosti) - British prosecutors said Tuesday they insisted that a Russian citizen suspected of murdering former security officer Alexander Litvinenko should be tried in London.

On Monday, Britain received Russia's official refusal to extradite businessman Andrei Lugovoi, whom British authorities accused of poisoning Litvinenko with radioactive Polonium-210 last November.

"The Russian authorities have declined to extradite Andrei Lugovoi," said Ken Macdonald, the head of the U.K. Crown Prosecution Service.

Russia's Prosecutor General's Office said that the Constitution bars Russian nationals from being extradited for trial, and said its cooperation with British law enforcement officials would be in line with Russian law and international treaties.

"They have said that they are prepared to put Mr. Lugovoi on trial in Russia if the evidence is forwarded to them," he said.

However, the chief prosecutor said Lugovoi had allegedly committed a grave crime by poisoning a British citizen in the British capital, and that therefore he had to be tried in the U.K.

British government officials blasted Russia for not being cooperative on a serious criminal matter and said London would have to consider a range of options to proceed with the Lugovoi criminal case.

"The Russian response is unacceptable," the Foreign Office said in a statement.

Andrei Lugovoi, also a former security officer, was accused by the Crown Prosecution Service on May 22 of murdering Litvinenko, who had fled to the U.K. in 2000, claiming his life was in danger after refusing an order to assassinate his patron Boris Berezovsky, a powerful Russian tycoon who fell out with the Kremlin and himself fled to the U.K. in 2001, where he was granted political asylum.

Though Litvinenko is thought to have been poisoned with radioactive Polonium-210, no official autopsy report has so far been made available. Lugovoi has vehemently denied the accusations against him, claiming they are politically motivated, and has in turn accused Litvinenko and Berezovsky of spying for MI6.