Britain expelled four Russian diplomats last week and said it would impose visa restrictions for officials over Moscow's refusal to extradite London's chief suspect in the fatal poisoning of the former FSB officer and British national in London last November.
Press secretary Anjoum Noorani said the embassy had set out the changes made to the visa regulations to the Russian authorities and would not discuss the details in public.
Earlier Wednesday, the Russian Foreign Ministry's official spokesman denied any changes.
"The Foreign Ministry has received requested explanations from the British Embassy in Moscow," Mikhail Kamynin told journalists. "They said no changes had been made [to visa regulations], and that the [new] rules introduced in April are still in effect."
But Kamynin said Russia would treat future visa requests from Britain adequately.
In early July, Russian prosecutors formally refused to extradite former Kremlin bodyguard-turned-businessman Andrei Lugovoi, accused by the U.K. of poisoning former Russian security officer and Kremlin critic Litvinenko with radioactive polonium, citing the Constitution.
Moscow responded to London's measures by expelling British diplomats and promised similar visa restrictions. The countries also suspended cooperation against terrorism.
