The White House scrambled to row back Joe Biden’s declaration that Vladimir Putin “cannot remain in power”, insisting he was not calling for a regime change.

In an impassioned speech in Warsaw, the US president appealed to Russian people directly, with comparisons between the invasion of Ukraine and the horrors of the Second World War.

“For God’s sake this man cannot remain in power,” the US president said at the close of his speech of the Russian president he earlier described as a “butcher”.

Mr Biden pleaded “if you’re able to listen: you, the Russian people, are not our enemy”, as multiple rockets struck the city of Lviv near the Polish border in the west of Ukraine.

But a White House official tried to argue that the US president’s point was that the Russian leader “cannot be allowed to exercise power over his neighbours or the region”.

“He was not discussing Putin’s power in Russia, or regime change,” the official added, before reports in the US suggested the remarks in question had not been scripted.

Mr Biden warned “we need to steel ourselves for the long fight ahead” as he conceded the battle will not be “won in days, or months either”.

He told European nations they must end “dependence on Russian fossil fuels”, but said sanctions had been sapping Russia’s strength and have reduced the rouble “to rubble”.

In the UK, Foreign Secretary Liz Truss said sanctions on oligarchs, banks and businesses could be lifted if Mr Putin ends the war and commits to “no further aggression”.

With the Kremlin’s troops struggling, her comments will be seen as a possible incentive for Mr Putin to cut his losses and broker a deal with Ukraine.

She told the Sunday Telegraph: “Those sanctions should only come off with a full ceasefire and withdrawal, but also commitments that there will be no further aggression.

“And also, there’s the opportunity to have snapback sanctions if there is further aggression in future. That is a real lever that I think can be used.”

Her remarks fit with those of her US counterpart Antony Blinken, who has said the travel bans and asset freezes are “not designed to be permanent”.

The secretary of state said the sanctions could “go away” in the event of an “in effect, irreversible” withdrawal of Russian troops.

Moscow has given an indication it could scale back its offensive to focus on what it claimed was the “main goal, liberation of Donbas”, the region bordering Russia in the east of Ukraine.

But Ukrainian president Volodymyr Zelensky warned he would not give up territory in peace talks as he noted that his troops have delivered “powerful blows” to invading forces.

Tobias Ellwood, the Conservative MP who chairs the Commons Defence Committee, described Mr Biden’s comment hinting at regime change as “unwise”.

He warned the Russian president will now see regime change as Mr Biden’s wider objective, adding: “Putin will spin this, dig in and fight harder.”

Mr Biden stopped at RAF Mildenhall, a base in Suffolk that supports US military operations, on his way back to Washington so that his Air Force One jet could refuel.