Keir Starmer has said he is prepared to put British troops on the ground in Ukraine if there is a deal to end the war with Russia, acknowledging it could put troops “in harm’s way” if Vladimir Putin launches another attack.

It is understood to be the first time the prime minister has explicitly stated he is considering deploying British peacekeepers to Ukraine. The comments came just before emergency talks with European leaders in Paris on Monday.

The leaders will aim to devise a strategy in response to Donald Trump’s push for a deal with the Russian president and to fears the US will reduce its defence commitments in Europe.

Starmer said the crisis was a “once in a generation moment” and an “existential” question for Europe.

Writing in the Daily Telegraph, he said the UK was “ready to play a leading role” in Ukraine’s defence and security, including the commitment of £3bn a year until 2030. Starmer said that, along with military aid to the country, “it also means being ready and willing to contribute to security guarantees to Ukraine by putting our own troops on the ground if necessary”.

“I do not say that lightly. I feel very deeply the responsibility that comes with potentially putting British servicemen and women in harm’s way,” Starmer said.

“But any role in helping to guarantee Ukraine’s security is helping to guarantee the security of our continent, and the security of this country.

“The end of this war, when it comes, cannot merely become a temporary pause before Putin attacks again.”

Since the Russian invasion of Ukraine began in February 2022, UK prime ministers have refused to publicly consider sending British soldiers to the country.

Starmer had previously suggested that British troops could be involved in safeguarding Ukraine after a ceasefire.

The UK’s prime minister, who is due to visit President Trump in Washington later this month, said: “While European nations must step up in this moment – and we will – US support will remain critical and a US security guarantee is essential for a lasting peace, because only the US can deter Putin from attacking again.”

Representatives of the US administration and Russian counterparts are expected to meet in Saudi Arabia for talks following Trump’s phone conversation with Putin on Wednesday.

But Ukrainian officials are not expected to be at the table at this stage and other European leaders might not be involved in the process at all.

Starmer added: “We must be clear that peace cannot come at any cost. Ukraine must be at the table in these negotiations because anything less would accept Putin’s position that Ukraine is not a real nation.”

He also warned of a repeat of the chaos after the withdrawal of US troops from Afghanistan in August 2021 under former president Joe Biden, which followed a deal struck with the Taliban under Trump.

“We cannot have another situation like Afghanistan, where the US negotiated directly with the Taliban and cut out the Afghan government,” Starmer said.

“I feel sure that President Trump will want to avoid this too.”