In President Joe Biden's most direct challenge yet to the Kremlin, the United States on Tuesday imposed sanctions to punish Russia for what it described as Moscow's attempt to poison opposition politician Alexei Navalny with a nerve agent last year.

Navalny, 44, fell ill on a flight in Siberia in August and was airlifted to Germany, where doctors concluded he had been poisoned with a nerve agent.

The Kremlin has denied any role in his illness and said it has seen no proof he was poisoned. Washington on Tuesday imposed sanctions against seven senior Russian officials and on 14 entities.

"All this is just an excuse to continue overt interference in our internal affairs," Maria Zakharova, a Russian foreign ministry spokeswoman, said in a statement on Wednesday.

"We do not intend to put up with this. We will respond based on the principle of reciprocity, but not necessarily symmetrically."

Russian Foreign Minister Sergei Lavrov said on Tuesday that Moscow would respond in kind to any new US sanctions, while Russia's envoy to the European Union also promised a response to EU sanctions on four senior Russian officials.

Zakharova said the US was free to choose whether it wanted "equal dialogue" with Russia on a reasonable basis, but said Moscow would pay no attention to any sanctions, which she said had failed in their aims in the past and would do so again now.

"Irrespective of America's 'sanctions addiction', we will continue to consistently and decisively defend our national interests, rebuffing any aggression. We urge our colleagues not to play with fire," said Zakharova.

Australian Associated Press