Joe Biden says Vladimir Putin 'cannot remain in power' as he likens invasion to WW2 horrors

• Joe Biden's speech delivered more than a hint of escalation, ITV News Peter Smith reports

President Joe Biden has said that Vladimir Putin "cannot remain in power" - in a dramatic escalation of rhetoric against the Russian leader after his brutal invasion of Ukraine.

The US president made the statement during a speech in Poland on Saturday, in which he compared the invasion of Ukraine and the horrors of World War Two.

But soon after Biden finished speaking the White House attempted to clarify his comments and said the president was not calling for a new government in Russia.

The White House issued this clarification: “The President meant that [Russian leader Vladimir] Putin should not be allowed to exercise power over his neighbours and the region. He did not discuss Putin's power in Russia or regime change.”

But the official who provided the comment declined to say whether Biden's statement about Putin was part of his prepared marks.

“For God’s sake, this man cannot remain in power," Biden said at the very end of a speech in Warsaw.

In response Kremlin spokesman Dmitry Peskov said that "it’s not up to the president of the US and not up to the Americans to decide who will remain in power in Russia.”

“Only Russians, who vote for their president, can decide that,” Peskov added. “And of course it is unbecoming for the president of the US to make such statements.”

Asked about the impact of such statements from Biden on Russia-US relations, Peskov described it as “extremely negative.”

“With each such statement, and Biden now prefers to make them daily, he is narrowing the window of opportunity for our bilateral relations under the current administration,” Peskov said.

Biden has frequently talked about ensuring that the Kremlin's invasion becomes a “strategic failure” for Putin and has described the Russian leader as a “war criminal."

But until his remarks in Warsaw, the American leader had not veered toward suggesting Putin should not run Russia. Earlier on Saturday, shortly after meeting with Ukrainian refugees, Biden called Putin a “butcher.”

In his speech in Warsaw, he also made a defence of liberal democracy and the NATO military alliance, while also saying Europe must steel itself for a long fight against Russian aggression.

As Biden met with Ukrainian refugees, Russia continued to pound cities, including in Lviv, the closest major Ukrainian city to Poland and a destination for the internally replaced that has been largely spared from major attacks.

In what was billed by the White House as a major address, Biden spoke in front of the Royal Castle, one of Warsaw's notable landmarks that was badly damaged during Adolf Hilter's war.

He told Russians they are not “our enemy” as he evoked the atrocities of the siege of Leningrad by the Nazis and made an impassioned defence of democracy.

“These are not the actions of a great nation,” Biden said.

“Of all people, you the Russian people, as well as all people across Europe still have the memory of being in a similar situation in the 30s and 40s, the situation of World War Two, still fresh in the mind of many grandparents in the region.

“Whatever your generation experienced, whether it experienced the siege of Leningrad, or heard about it from your parents and grandparents, train stations overflowing with terrified families fleeing their homes, nights sheltering in basements and cellars, mornings sifting through the rubble in your home – these are not memories of the past – not any more, it’s exactly what the Russian army is doing in Ukraine right now.”

Biden borrowed the words of Polish-born Pope John Paul II and cited anti-communist Polish dissident and former president, Lech Walesa, as he warned that Putin's invasion of Ukraine threatens to bring “decades of war.”

"In this battle we need to be clear-eyed. This battle will not be won in days, or months, either,” Biden said.

“We must commit now, to be this fight for the long haul."

The crowd of about 1,000 included some of the Ukrainian refugees who have fled for Poland and elsewhere in the midst of the brutal invasion.

Biden also rebuked Putin for his claim the the invasion sought to “de-Nazify” Ukraine. The president of Ukraine. Volodymyr Zelensky, is Jewish and his father’s family died in the Holocaust.

“Putin has the gall to say he’s de-Nazifying Ukraine. It’s a lie,” Biden said. “It’s just cynical. He knows that and it’s also obscene.”

The president defended the 27-member NATO alliance that Moscow says is increasingly a threat to Russian security. He noted that NATO had worked for months through diplomatic channels to try to head off Russia's invasion.

“The Kremlin wants to portray NATO enlargement as an imperial project aimed to destabilise in Russia,” Biden said. “NATO is a defensive alliance that has never sought the demise of Russia.”

After meeting with refugees at the National Stadium, Biden marveled at their spirit and resolve in the aftermath of Russia’s deadly invasion as he embraced mothers and children and promised enduring support from Western powers.

Biden listened intently as children described the perilous flight from neighbouring Ukraine with their parents. Smiling broadly, he lifted up a young girl in a pink coat and told her she reminded him of his granddaughters.

The president held hands with parents and gave them hugs during the stop at the soccer stadium where refugees go to obtain a Polish identification number that gives them access to social services such as health care and schools.

Some of the women and children told Biden that they fled without their husbands and fathers, men of fighting age who were required to remain behind to aid the resistance against Putin's forces.