The Kremlin said on Thursday it hoped that U.S. President Joe Biden had meant to say Ukraine rather than Iraq when he made a verbal slip-up on Wednesday.

Biden had said that Russian President Vladimir Putin was "losing the war in Iraq" when he meant to say Ukraine.

Asked to comment on Biden's slip-up, Kremlin spokesman Dmitry Peskov said: "We are interested in this, we are monitoring the situation very carefully and we hope that Mr. President had Ukraine in mind during yesterday's statement," Peskov told a news briefing.

Peskov added that he could not comment on the health of the 80-year-old U.S. president.

Speaking to reporters in Washington, Biden was asked if Putin had been weakened by a brief uprising last Saturday led by a Russian mercenary chief whose forces had been fighting in Ukraine.

"It's hard to tell really. But he's clearly losing the war in Iraq. He's losing the war at home and he has become a bit of a pariah around the world," Biden had said.

It was his second slip-up in 24 hours. On Tuesday night, Biden corrected himself at a campaign fundraising event - referring to China when he meant India, whose prime minister, Narendra Modi, visited the White House a week ago.

Public opinion polling shows that a majority of Americans have concerns about Biden's age. The president's doctor declared him healthy and "fit for duty" in February after a physical examination.

Biden, who has regularly pledged continued military, financial and other U.S. aid to Ukraine in its war with Russia, said on Monday the aborted mutiny in Russia was part of a struggle within the Russian system and that the United States and its allies were not part of it.