Ukraine must be placed in the “strongest possible position for negotiations” to end the war with Russia, Sir Keir Starmer has said.

The Prime Minister insisted the UK will back Ukraine “for as long as it takes” as he made a speech at the Lord Mayor’s Banquet in London, but for the first time acknowledged the conflict could move towards a negotiated end.

Ukrainian President Volodymyr Zelensky has in recent weeks suggested he is open to a possible ceasefire with Vladimir Putin’s Russia.

Kyiv and its European allies meanwhile fear the advent of Donald Trump’s return to the White House could result in American aid being halted.

President-elect Trump has said he would prefer to move towards a peace deal, and has claimed he could end the conflict on “day one” of his time in power.

As he attempts to strike up a good relationship with the incoming president, Sir Keir revealed he had told Mr Trump the UK “will invest more deeply than ever in this transatlantic bond with our American friends in the years to come”.

Prime Minister Sir Keir Starmer during the annual Lord Mayor’s Banquet at the Guildhall in central London
Prime Minister Sir Keir Starmer during the annual Lord Mayor’s Banquet at the Guildhall in central London (Yui Mok/PA)

In his speech at London’s Guildhall, the Prime Minister said there is “no question it is right we support Ukraine”, as the UK’s aid to Kyiv is “deeply in our self-interest”.

Allowing Russia to win the war would mean “other autocrats would believe they can follow Putin’s example,” he warned.

Sir Keir added: “So we must continue to back Ukraine and do what it takes to support their self-defence for as long as it takes.

“To put Ukraine in the strongest possible position for negotiations so they can secure a just and lasting peace on their terms that guarantees their security, independence, and right to choose their own future.”

Mr Zelensky told Sky News over the weekend he would be open to speaking with Mr Putin, but branded the Russian president a “terrorist”.

Prime Minister Sir Keir Starmer (centre) with Lord Mayor of the City of London Alastair King (centre left) during the annual Lord Mayor’s Banquet at the Guildhall in central London
Prime Minister Sir Keir Starmer (centre) with Lord Mayor of the City of London Alastair King (centre left) during the annual Lord Mayor’s Banquet at the Guildhall in central London (Yui Mok/PA)

He also suggested Ukrainian territory under his control should be taken under the “Nato umbrella” to try to stop the “hot stage” of the war with Russia.

In a banquet speech focused on foreign affairs, the Prime Minister said it was “plain wrong” to suggest the UK must choose between its allies, adding: “I reject it utterly.

“(Clement) Attlee did not choose between allies. (Winston) Churchill did not choose.

“The national interest demands that we work with both.”

Sir Keir said the UK and the US were “intertwined” when it came to commerce, technology and security.

The Prime Minister added: “That’s why, when President Trump graciously hosted me for dinner in Trump Tower, I told him that we will invest more deeply than ever in this transatlantic bond with our American friends in the years to come.”

He also repeated his commitment to “rebuild our ties with Europe” and insisted he was right to try to build closer links with China.

“It is remarkable that until I met President Xi last month there had been no face-to-face meeting between British and Chinese leaders for six years,” the Prime Minister said.

Prime Minister Sir Keir Starmer speaks during the annual Lord Mayor’s Banquet at the Guildhall in central London
Prime Minister Sir Keir Starmer speaks during the annual Lord Mayor’s Banquet at the Guildhall in central London (Yui Mok/PA)

“We can’t simply look the other way. We need to engage. To co-operate, to compete and to challenge on growth, on security concerns, on climate as well as addressing our differences in a full and frank way on issues like Hong Kong, human rights, and sanctions on our parliamentarians,” he added.

The Prime Minister said he wants Britain’s role in the world to be that of “a constant and responsible actor in turbulent times”.

He added: “To be the soundest ally and to be determined, always, in everything we do.

“Every exchange we have with other nations, every agreement we enter into to deliver for the British people and show, beyond doubt, that Britain is back.”

Ahead of Sir Keir’s speech, Lord Mayor Alastair King urged the Prime Minister and his Government to loosen regulations on the City of London to help it maintain its competitive edge.

In an echo of Sir Keir’s commitment to drive the UK’s economic growth, the Lord Mayor said: “The idealist will dream of growth, but the pragmatist understands that our most effective machinery to drive growth is here in the City, in the hands of some of the brightest and most committed people that you will find anywhere in the world.”