A billionaire businessman who is reported to have millions in the Isle of Man is at the centre of a campaign to deselect Conservative MPs in the UK.

Arron Banks is a key shareholder in the Manx Financial Group, as well as owning stakes in more than a dozen companies based offshore.

He is an arch Brexiteer, having donated millions to the campaign for Britain to leave the EU.

Now he is turning on MPs he believes threaten the UK’s withdrawal.

A ’dirty dozen’ MPs have been listed in the ’Blue Wave’ campaign.

It is calling for Brexiteers to join the Conservative party in certain constituencies, so that there could be enough members for the local party to deselect the sitting MP.

Many MPs fear that his Blue Wave could become a right-wing version of the Momentum movement, in which supporters of Jeremy Corbyn have flooded the Labour Party membership over the past two years, changing the party into a much more leftwing group.

They worry that this could make the Tory party more hardline on issues ranging from the EU to crime and punishment and public spending.

Tom Watson, the deputy leader of the Labour party, tweeted: ’Arron Banks is using his private wealth to bully democratically-elected MPs who dare to challenge his wrecking-ball politics.

’It is more important than ever that people know what is actually going on.’

Banks was accused by Michael Crick, political reporter with Channel 4 News, of putting the ’frighteners’ on remain-leaning MPs.

’There’s an element of that,’ he replied. ’I’m not going to deny that.’

He added: ’They stood on a manifesto of leaving the customs union and leaving the single market.

’Now these people are campaigning for a second "people’s vote".’

At the top of the ’dirty dozen’ list is Damian Collins, the MP for Folkstone.

In fact, Collins has never advocated a people’s vote and has never opposed any Brexit legislation.

He told Crick that Banks’s behaviour was a disgrace.

Collins and Banks clashed when Banks was called to give evidence to the Commons culture committee, which Collins chairs.

That meeting asked Banks where his money came from and questioned his business dealings with Russia.

Banks astonished MPs on the committee by leaving that meeting abruptly, saying he had a lunch date.

When Collins pressed him for five more minutes, Mr Banks responded: ’No, no, no - the word is "no".’

On Channel 4 News, Collins told Crick that Banks was free to encourage people to join the Conservative party if he wanted to. ’This is a very wealthy man who has taken exception against being questioned in public and has decided to take this out against people like me who he thinks shouldn’t be poking our noses into his affairs,’ he said.

’He is the biggest donor in British political history and we don’t know very much about him and his money and where it comes from.

’He keeps a lot of it offshore in the Isle of Man.

’I think we should be calling people like that to account.’

Crick told viewers: ’This is a hugely significant development in British politics.

’Rarely can so much money have been spent outside an election campaign at a constituency level.’

He said Banks was spending £38,000 to send the letter to voters in Collins’ constituency in Folkstone.

It includes a request for further donations to extend the deselection campaign.

Online advertisements have appeared on social media from what Crick describes as ’groups connected with Banks’ targeting constituents of the ’dirty dozen’.

Anna Soubry, the MP for Broxtowe in Nottinghamshire, is probably the best-known politician on the Brexiteers’ hit list.

Another MP on the list, Philip Lee, who represents Bracknell, said the letter’s content had malign intent.

On Channel 4 News, Banks denied he was bankrolling the campaign.

’We have raised this money from the general public,’ he told Crick.

’It is money that has been donated, so Arron Banks has not spent a single penny on this.’

Crick asked: ’Do you expect us to belive that?

’You donated six or seven million pounds to the Brexit campaign.

’Here you are a multi-millionaire and you are suggesting that none of your money has been give to this.’

Banks responded: ’We can absolutely prove that. We have got the list of small donations.

’Leave.eu was left with nearly 100,000 members. It’s got nearly 1.5m people following it on social media.

’The donations came from small people interested in the Brexit campaign.’