Boris Johnson has rejected Nigel Farage's offer to form a "Leave alliance".

With the general election campaign now under way, the prime minister told Sky's Sophy Ridge: "I've ruled out a pact with everybody because I don't think it's sensible to do that.

Brexit Party leader Mr Farage said on Friday he would hold back from fielding a candidate in every seat in Britain if the PM dropped his EU Withdrawal Agreement and joined him in a "non-aggression pact".

But Mr Johnson insisted he would not do a deal with any party leader over the 12 December election.

He said: "The only likely consequence of voting for them [other party leaders], rather than for us as Conservatives, is that you are making it more likely that you will get Jeremy Corbyn and Labour and a chaotic constellation of other parties... with nothing but dither and delay."

Mr Johnson also rejected Donald Trump's claim that his EU deal may hinder a future trade deal between the US and UK.

The prime minister said: "I'm afraid I don't wish to cast any aspersions on the president of the United States, but in that respect he is patently in error, anybody who looks at our deal can see it is a great deal.

"What it does is it allows us to take back control of our money, our borders and our laws, but also it allows us to have full unfettered control of our tariff schedules in Geneva and to do it as one United Kingdom.

"That deal is ready to go, we've negotiated it. People said it wasn't possible. But there it is."

Mr Johnson also said he was "sorry" the UK did not leave the European Union on 31 October which he had pledged to make happen "do or die".

He told Sophy Ridge: "It's a matter of deep regret. All we need to do now is get on and do it."

Launching the Brexit Party's general election campaign, Mr Farage claimed the PM's deal did not represent Brexit and described his "very big, generous offer" as a "one-off opportunity" that would secure Brexit and win the election with a "big stonking majority".

Speaking to Mr Farage on his radio show on Thursday, the US president said he had doubts over Mr Johnson's deal with the EU.

"Under certain aspects of the deal you can't do it," he said. "You can't do it, you can't trade, we can't make a trade deal with the UK.

"I think we can do many times the numbers that we're doing right now and certainly much bigger numbers than you're doing under the EU. So, I know Boris wants to be very careful of that."