"As of today, we have received from U.K. authorities only the most general information on the case. We are expecting the British side to provide... more detailed information," the ministry said in a statement.
British prosecutors announced earlier Tuesday that they would seek the extradition of Lugovoi to charge him with poisoning Kremlin critic and former FSB officer Litvinenko last November. However, the Russian Prosecutor General's Office ruled out the possibility of extradition, saying Lugovoi could only be brought to account in Russia.
The ministry statement said Russia has repeatedly voiced its readiness to cooperate with its U.K. colleagues in a thorough and unbiased investigation of the case.
"As for the extradition issue, it is known that extradition of Russian citizens to foreign states is out of line with the Russian Constitution. There are similar provisions in other states' legislations," the Russian ministry said.
Litvinenko, who received U.K. citizenship a few weeks before his fatal radioactive poisoning November 1 last year, accused Russia's president of orchestrating his death, a charge that Vladimir Putin dismissed as ridiculous. The case, investigated both in London and Moscow, has strained relations between the countries.
Lugovoi, a former security officer turned businessman, who has vehemently denied complicity in the murder, protested his innocence again Tuesday, and said the accusations from the Crown Prosecution Service were politically motivated.
