The prime minister has said Russian oligarch Roman Abramovich must "pay up now" to victims of the war in Ukraine or face court action.

Mr Abramovich, the former owner of Chelsea Football Club, pledged in 2022 that the £2.5bn he made from the sale of the club would be used to benefit victims of the Russian invasion of Ukraine.

But there has been a delay in releasing the funds, which are currently frozen in a British bank account, due to a standoff over how exactly they should be used.

Sir Keir Starmer told the Commons on Wednesday: "My message to Abramovich is clear: the clock is ticking."

The government wants the money to be used for humanitarian aid, but Mr Abramovich insisted it should be used for "all victims of the war" – meaning that Russians could also benefit.

The oligarch cannot access the money under UK sanctions but the proceeds from the Chelsea sale still legally belong to him.

Updating MPs, Sir Keir said the UK had issued a licence "to transfer £2.5bn from the sale of Chelsea Football Club that's been frozen since 2022."

And, in a warning to Abramovich, he said: "Honour the commitment that you made and pay up now, and if you don't we're prepared to go to court and ensure that every penny reaches those whose lives have been torn apart by Putin's illegal war."

And Foreign Secretary Yvette Cooper told the BBC Mr Abramovich "needs to honour that commitment, pay that money".

Asked if a legal battle could drag out the process for years, Ms Cooper said: "I'm urging him not to try and pursue further court action."

But she confirmed the government will take the matter to court if he does not act.

Mr Abramovich's representatives declined to comment.

The Treasury said that under the terms of the licence, the money must go to "humanitarian causes" in Ukraine and cannot benefit Mr Abramovich or any other sanctioned individual.

The government first threatened to sue Mr Abramovich in June.

Chancellor Rachel Reeves said: "It is unacceptable that more than £2.5bn of money owed to the Ukrainian people can be allowed to remain frozen in a UK bank account."

Mr Abramovich – a Russian billionaire who made his fortune in oil and gas – was granted a special licence to sell Chelsea following Russia's invasion of Ukraine, providing he could prove he would not benefit from the sale.

He is alleged to have strong ties to Russian President Vladimir Putin, something he has denied.

It is understood that Mr Abramovich has 90 days to act before the UK considers taking legal action.

On Thursday, EU leaders are set to review proposals to use proceeds from frozen Russian assets to support Ukraine's huge budget and defence needs. Russia has fiercely opposed the proposals.