British Prime Minister Boris Johnson has rejected Donald Trump's advice of forming a Brexit pact with Nigel Farage in the pre-Christmas general election.

The US president staged a major intervention by calling for Mr Johnson to team up with the Brexit Party leader to form an "unstoppable force" for the 12 December vote.

But Mr Johnson declined to take up the advice of his close ally, who had also waded into UK politics to deliver a criticism of Mr Johnson's new Brexit deal and Jeremy Corbyn.

Asked if he would form an alliance with Mr Farage, the Prime Minister told ITV News: "I may respectfully say to all our friends around the world... that the only way to get this thing done is to vote for us.

"Vote for this Government because unfortunately, as I tried to point out, if you vote for any other party the risk is you'll just get Jeremy Corbyn, the Labour Party, dither and delay, not just one referendum next year but two referendums."

A Number 10 source confirmed that this explicitly meant no deals with the Brexit Party.

"The PM is clear that only a vote for the Conservatives will deliver not just on the Brexit deal but on the priorities people care about," the source told the PA news agency.

Earlier, Mr Farage warned Mr Johnson to drop his Brexit deal or the Brexit Party will put up candidates for every seat in the British general election.

The Brexit Party leader was speaking at the launch of his party's election campaign in London.

Mr Farage said that Mr Johnson had until 14 November to agree to his demands.

Johnson and Farage would be unstoppable force - Trump

If the government does not agree "then the Brexit Party will be the only party standing in these elections that actually represents Brexit," Mr Farage said.

"We will contest every seat in England, Scotland and Wales. Don't doubt that we are ready."

Mr Farage said an option would be a "non-aggression pact" with Mr Johnson, describing it as a "one-off opportunity".

He would not say whether or not he is standing in the election, saying that would become clear in the coming days.

Mr Farage said the campaign launch is about the party making clear it is "very, very prepared to compromise".

He added that the only way to get Brexit done is to "form a Leave alliance" and win the election with a "big stonking majority".

Mr Farage hit out at the "broken promises" of the British government after it failed to meet the Brexit deadline of 31 October.

He said that Mr Johnson's Withdrawal Agreement with the European Union was "not Brexit," adding "I say to Boris Johnson - drop the deal."

Meanwhile, the first televised election debate between Mr Johnson and Mr Corbyn has been set for 19 November.

The debate will be aired on ITV and it will be the first time the party leaders go head to head in the election campaign.

The Labour Party leader challenged Mr Johnson to a debate earlier in the week, and said it was "welcome" that he accepted.

"This is a once in a generation election. So it's welcome that Boris Johnson has accepted our challenge of a head to head TV debate. The choice could not be clearer: Boris Johnson's Conservatives protecting the privileged few or a Labour government on the side of the many," Mr Corbyn tweeted.

Mr Johnson also took to Twitter to comment on the debate.

"Looking forward to making the positive case to the country that we should #GetBrexitDone & deliver on the people's priorities - #OurNHS, schools, tackling crime & the cost of living," he said.

The Prime Minister was accused of running scarred from TV debates by rival Jeremy Hunt during the race to take over the Tory Party after the departure of Theresa May.

Mr Johnson did take part in two one-on-one debates during the battle for the Tory crown, but not before Mr Hunt and others placed him under great pressure to do so.

Additional reporting Reuters