Sir Keir Starmer has said the UK was not involved in the US operation in Venezuela, in which the country’s president, Nicolás Maduro, and his wife were “captured” by special forces and the capital, Caracas, hit with airstrikes.

Speaking for the first time since Donald Trump launched his extraordinary attack, the prime minister said he had not spoken to the US president, and that the UK was keen to establish “the facts” of what had happened.

Starmer said the government was working with the British embassy in Caracas to support the 500 Britons in Venezuela.

Speaking to broadcasters, the PM said: “It’s obviously a fast-moving situation and we need to establish all of the facts.

“The UK was not involved in any way in this operation, and as you would expect we are focusing on British nationals in Venezuela and working very closely with our embassy, and so we want to talk to the president, I will want to talk to allies, but at the moment we need to establish the facts.”

He added that he was waiting for more details to emerge from a press conference to be held by Trump later on Saturday.

Starmer said: “I always say and believe we should all uphold international law, but I think at this stage, a fast-moving situation, let’s establish the facts and take it from there.”

The prime minister had been urged to denounce the operation by US forces. Liberal Democrat leader Sir Ed Davey said the action was “illegal” and could embolden other world leaders.

In a post on X he said: “Keir Starmer should condemn Trump’s illegal action in Venezuela.

“Maduro is a brutal and illegitimate dictator, but unlawful attacks like this make us all less safe.

“Trump is giving a green light to the likes of Putin and Xi to attack other countries with impunity.”

Green party leader Zack Polanski agreed, posting on the same platform that Starmer and Yvette Cooper, the foreign secretary, should oppose it.

Polanski said: “After years of arming a genocide and worshipping the ‘special relationship’, Trump now believes he can act with impunity.”

He later responded to Starmer’s comments and said: “Starmer says he wants to establish facts by watching Donald Trump’s press conference. People said giving [Trump] a second state visit was a genius move of strategy – really seems to have paid off.

“Special relationship – alive and kicking.”

Reform UK leader Nigel Farage called the operation “unorthodox”, and acknowledged it broke international law. However, he added: “If [it] makes China and Russia think twice, it may be a good thing.

“I hope the Venezuelan people can now turn a new leaf without Maduro.”

Conservative party leader Kemi Badenoch has not publicly commented on the developments.