LONDON — He’s branded one U.S. ally's government “fascists” and another leader a “fool.” Now, Elon Musk has labeled Britain a “tyrannical police state” while endorsing calls for a new election and boosting a video from a jailed far-right activist.

Musk, not just the world’s richest man but a key adviser to President-elect Donald Trump, has clashed for months with Prime Minister Keir Starmer at a time when the U.K. is concerned about its standing with the incoming U.S. administration. 

Over the weekend the tech billionaire took his feud to a new level, taunting the U.K.'s new center-left leader over sinking approval ratings and questioning why far-right figurehead Tommy Robinson had been imprisoned.

"The people of Britain have had enough of a tyrannical police state," Musk posted on his X platform, quoting a post about an online petition calling for another election that has now reached 2 million signatures.

Starmer's Labour Party won an overwhelming majority in July and does not need to call a vote for another five years. But his leadership has been beset by an immediate sense of crisis, low approval ratings and more recently a mass protest by angry farmers. The petition accuses the government of having "gone back on the promises" it made during the election.

Musk drew criticism from the U.K. in August, when he said the country was on the verge of “civil war” following days of right-wing riots after three young girls were killed in a knife attack at a Taylor Swift-themed dance party.

But his latest attacks carry more weight on the heels of Trump's election victory, with Musk lined up to run a new government efficiency drive and having apparent input on foreign affairs.

As Starmer's government works to overcome its own past public comments and build relations with Trump, Musk continues to attack it.

NBC News has reached out to the Trump campaign team for comment.

Earlier in November Musk weighed in on the farmers' protests, accusing the U.K. of going "full Stalin" as it increased inheritance tax on farms worth more than $1.25 million, an allusion to the Soviet Union's devastating farm collectivization policies under Joseph Stalin.

Then on Saturday, Musk reposted a graph showing Starmer’s declining approval ratings.

Musk, who is known for picking fights online and retweeting far-right posts, also shared a post Saturday by Robinson — the jailed far-right activist and founder of the anti-immigrant English Defence League.

Robinson is currently serving an 18-month prison sentence after admitting contempt of court by repeating false claims against a Syrian refugee.

“Why is he in prison for 18 months?” Musk posted.

Musk has a history of boosting far-right voices on X, allowing conspiracy theorists and extremists back onto the social media platform after he became CEO and sharing their content.

Asked about Musk's comments Monday, a spokesperson for Starmer said the prime minister looked forward to working with Trump and "his whole team, including Elon Musk” to develop “the special U.K.-U.S. relationship,” according to Politico.

NBC News has reached out to Starmer's office for further comment.

Britain is not the only U.S. ally Musk has assailed publicly in recent weeks.

He has criticized Australia's proposed ban on social media for children under 16 and previously called the Australian government “fascists” over plans to crack down on misinformation online. Earlier this month he called German Chancellor Olaf Scholz a "fool" after his ruling coalition imploded.

Reference: NBC News