Nigel Farage has said he is prepared to fight a by-election in South Thanet if claims about election spending are upheld and a rerun is ordered.

The Ukip leader had said he would be retiring from frontline politics but appears to to be having second thoughts.

The Conservatives are facing a probe into their election expenses during the campaign for the Kent constituency and if they are upheld a by-election could be triggered.

Mr Farage said that if that was the case he would return to the fray despite announcing in summer that he was to stand down as Party leader.

In an interview with the Mail on Sunday, Mr Farage said the Conservatives were becoming anxious over the possibility of a rerun in Thanet should the investigation uphold claims that certain expenses were not properly reported.

He said: "I suspect one of the reasons Downing Street is being so vile about me – just when I can play a positive role with Trump – is because they are worried this may come back to bite them."

Asked if he would stand as the party’s candidate in any by-election, he replied: "I’d have to."

He joked that he could even bring Donald Trump over to campaign on his behalf.

Mr Farage was defeated by Craig Mackinlay in 2015 after a bitter and acrimonious campaign. It was his seventh attempt at the coming an MP.

Immediately after result he resigned as party leader only to return to the role just weeks later.

He remains interim leader and has seized the headlines in the wake of the presidential election by becoming the first UK politician to have a meeting with Donald Trump.

Ukip is facing separate claims about its own election spending in South Thanet after EU auditors said money allocated to the MEPs group to which the party belongs had being wrongly used on polling research during the general election campaign in 2015.

Mr Farage said the auditors were wrong and any money had been spent within the rules.