Updated 12:00

Downing Street has hit back at the former UK Foreign Secretary over his attack on the UK Prime Minister’s Brexit strategy.

In an article in the Telegraph today Boris Johnson claimed Brexit negotiations are rigged, with the inevitable outcome of a victory for the EU."

He said negotiators had "gone into battle with the white flag fluttering over our leading tank."

This afternoon however, a spokesperson for UK Prime Minister Theresa May her 'Chequers plan’ for the future relationship between the two blocs was "the only credible and negotiable plan that has been put forward” by the UK side and insisted it will “deliver on the will of the British people.”

He also noted that Mrs May was a “serious prime minister and has put forward serious proposals" - fuelling a growing row with the former foreign secretary.

Asked if she would make further concessions in the talks, the spokesman did not rule it out, but added: "We have now made our move and it's for the EU to make theirs."

File photo of former British Foreign Secretary Boris Johnson and British Prime Minister Theresa May, 03-09-2018. Image:  Thierry Charlier/AP/Press Association Images

Earlier, Mr Johnson claimed the Irish border issue was being used by London and Brussels as a means of preventing a “proper” Brexit.

He accused “some” UK Government ministers of deliberately using the Irish border "to keep Britain effectively in the customs union and in the single market."

The row has the potential to push fault lines in the Conservative Party over Brexit even further apart.

"The fix is in"

Writing in the Daily Telegraph, he said: "Out of their corners come Dominic Raab and Michel Barnier, shrugging their shoulders and beating their chests - and I just hope you aren't one of those trusting souls who still thinks it could really go either way.”

"The fix is in. The whole thing is about as pre-ordained as a bout between Giant Haystacks and Big Daddy; and in this case, I am afraid, the inevitable outcome is a victory for the EU, with the UK lying flat on the canvas and 12 stars circling symbolically over our semi-conscious head."

Mr Johnson said that the real "scandal" is "not that we have failed, but that we have not even tried" on Brexit.

He accused "some" of the government of deliberately using the Irish border situation to "stop a proper Brexit."

Good deal

The attack comes the day after Mrs May wrote in the same newspaper that she said she was "confident" that the government could strike "a good deal" and in the event of a no-deal Britain would "be ready if we need to be" and "go on to thrive."

However, Mr Barnier, the EU's chief Brexit negotiator, has delivered his most withering verdict condemnation yet of Mrs May's plans, saying they would "end" the European project.

With Parliament returning from its summer break on Tuesday, speculation that the PM will face a co-ordinated effort from Tory hardline Brexiteers to abandon her exit plan has been rife.

Election strategist Sir Lynton Crosby is involved in a "chuck Chequers" campaign, it has been reported.

"Diddly squat"

Mr Johnson says Britain faces getting "two-thirds of diddly squat" for its divorce bill in response to Mr Barnier's comments that he "strongly opposed" the "cherry-picking" Chequers proposals.

Mr Johnson says: "They may puff about 'cherry-picking' the single market. There may be some confected groaning and twanging of leotards when it comes to the discussion on free movement. But the reality is that in this negotiation the EU has so far taken every important trick.

"The UK has agreed to hand over £40bn of taxpayers' money for two-thirds of diddly squat.

"We will remain in the EU taxi; but this time locked in the boot, with absolutely no say on the destination. We won't have taken back control - we will have lost control."

The comments followed claims from former Brexit secretary David Davis that Mrs May had positioned herself for "open sesame" on further Brexit climbdowns after saying she would not be pushed into compromises "that are not in our national interest."

Mr Davis branded the Chequers blueprint as being "actually almost worse than being in" the EU.

Scottish independence

Meanwhile, research carried out for pro-European group Best for Britain indicated there could be a majority for Scottish independence in Scotland following Brexit.

Additionally, today sees the launch of a new campaign group called Women for a People's Vote.

The group aims to "put women's voices at the front" of the Brexit debate, as a YouGov poll commissioned by the People's Vote Campaign finds only 13% of women think it is likely that Britain will get a good Brexit deal.