MOSCOW: Moscow said Monday it regretted that Washington did not respond to President Vladimir Putin's proposal to organise public talks with US President Joe Biden.

"One more opportunity has been passed up to look for a way out of the dead end in Russia-US ties," the Russian foreign ministry said in a statement.

"Responsibility for that rests fully with the United States."

Putin last week offered to hold virtual talks with Biden after the American leader described him as a "killer".

He suggested that the two leaders have an "open direct discussion", inviting Biden to hold a "live broadcast" on either Friday or Monday.

Biden told reporters on Friday that the two would speak "at some point".

In an interview with ABC News on Wednesday, when asked if he thought Putin, who has been accused of ordering the poisoning of opposition figure Alexei Navalny, is "a killer", Biden said: "I do."

Putin later mocked the US leader's remarks, saying "it takes one to know one" and wishing the 78-year-old Biden good health.

The US president's remarks sparked the biggest crisis in bilateral relations in years, with Russia ordering its Washington ambassador back to Moscow for urgent consultations in an unprecedented move in recent diplomatic history.