Left-wing MPs have demanded Sir Keir Starmer denounces Donald Trump's extraordinary strikes on Venezuela and capture of Nicolas Maduro.
Richard Burgon, who chairs the Socialist Campaign Group, urged the PM to "stand up to Trump's gangster politics" and "respond to an illegal bombing and kidnapping by Trump in exactly the way he would if Putin had carried it out".
"Either Keir Starmer believes in international law - or he doesn't," Mr Burgon said.
On Sunday, he will join an "emergency online rally" for which attendees could buy "top-tier solidarity tickets" for £30.
Campaigners, activists and more will be demanding the "safe return" of dictator Mr Maduro and an end to "US regime change".
They will then stage an in-person protest outside Downing Street.
Fellow Labour MPs Jon Trickett, Kim Johnson and Kate Osborne have also pushed for a firmer response.
Independent MP Diane Abbott then raged: "If you cannot say this is illegal, all your talk of human rights, the law and democracy is so much hot air."
Despite the fury, Sir Keir appeared to have been totally uninvolved with Venezuela - and even caught off-guard by Saturday's air strikes.
Left-wing MPs have demanded Sir Keir Starmer denounces Donald Trump's extraordinary strikes on Venezuela
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Diane Abbott and other hard-left MPs also voiced their fury at the PM
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The Prime Minister told broadcasters he wanted to first "establish the facts" and speak to Mr Trump before commenting on the decision to launch military action.
Asked if he had spoken to Mr Trump, he said: "No, I haven't, and it's obviously a fast-moving situation and we need to establish all the facts."
Downing Street is said not to have been informed about the operation beforehand.
The US and UK typically share intelligence on military operations through the Five Eyes alliance.
BRITAIN REACTS WHILE AMERICA ACTS - READ MORE:
Richard Burgon promoted the 'emergency online rally' to his social media followers
|VENEZUELA SOLIDARITY CAMPAIGN
Sir Keir stressed that Britain played no part in the military action.
"What I can say is that the UK was not involved in this operation. As you can expect, we are focusing on British nationals in Venezuela and working very closely with our embassy," he said.
The Prime Minister also suggested he did not approve of the strikes.
He later said: "The UK has long supported a transition of power in Venezuela. We regarded Maduro as an illegitimate president and we shed no tears about the end of his regime."
Nicolas Maduro was caught, arrested and charged within just hours of the US airstrikes
| WHITE HOUSEThe Government plans to discuss the situation with US counterparts in coming days.
Mr Trump's allies maintain the operation was lawful, arguing it fulfilled a federal arrest warrant against Mr Maduro on drug trafficking charges.
The US President announced on Truth Social that Mr Maduro and his wife had been "captured and flown out of the country".
The couple were later seen being led into the US Drug Enforcement Administration offices in New York City.
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