First King George III. Now Sir Keir Starmer.

Citing the American revolution while misspelling “Britian”, Donald Trump’s campaign has filed an extraordinary complaint against the UK’s Labour party for what it claims is “interference” in the US presidential election.

The Trump campaign alleged that in recent weeks, Labour recruited and sent party members to campaign for his opponent, Kamala Harris, in critical battleground states in a bid to influence the 5 November election.

“When representatives of the British government previously sought to go door-to-door in America, it did not end well for them,” says a letter from Trump’s legal team to the Federal Election Commission in Washington.

“This past week marked the 243 anniversary of the surrender of British forces at the Battle of Yorktown, a military victory that ensured that the United States would be politically independent of Great Britian” – an incorrect rendering of “Britain”.

It is understood that volunteers are campaigning in the US in their own personal time, rather in their capacity working for the the Labour party.

The letter goes on to request an immediate investigation into “blatant foreign interference” in the election in the form of “apparent illegal foreign national contributions made by the Labour Party of the United Kingdom” and accepted by Harris’s campaign committee.

It also refers to a report in the Washington Post that claims advice has been offered between Labour and the Harris campaign, and other reports regarding meetings between senior Labour staff and the Democratic campaign.

Those referenced in the letter include Matthew Doyle, Downing Street director of communications, and Morgan McSweeney, the prime minister’s chief of staff.

The complaint references a social media post, which appears to have been deleted, in which Sofia Patel, head of operations at Labour, posted on LinkedIn last week that 100 current and former party staffers were headed to the US to campaign for Harris.

The letter refers to a “volunteer exemption” in US elections which means foreign nationals can volunteer, but the letter states “they may not be compensated, foreign nationals may not make expenditures, and they may not direct or control activities of US campaigns”.

Last week’s post received a swift backlash from Republicans, with far-right representative Marjorie Taylor Greene writing on X that “foreign nationals are not allowed to be involved in anyway in US elections”.

And Elon Musk, the billionaire entrepreneur backing Trump, wrote on X, the social media platform he owns: “This is illegal” – only to delete the post after a community note pointed out there is no law preventing foreigners from participating in unpaid door-knocking.

The Trump campaign followed up on Tuesday with its legal complaint. Susie Wiles, co-manager of the campaign, said: “In two weeks, Americans will once again reject the oppression of big government that we rejected in 1776. The flailing Harris-Walz campaign is seeking foreign influence to boost its radical message – because they know they can’t win the American people.

“President Trump will return strength to the White House and put America, and our people, first. The Harris campaign’s acceptance and use of this illegal foreign assistance is just another feeble attempt in a long line of anti-American election interference.”

Starmer, the British prime minister, met Trump, the former US president, during a trip to New York last month. Starmer visited Trump Tower, saying he wanted to meet Trump face to face because “I’m a great believer in personal relationships on the world stage”.