The British Prime Minister has spoken to her Irish counterpart Leo Varadkar this afternoon about the ongoing dispute over a potential hard border with Northern Ireland, according to a Downing Street statement.

On Monday the pair had agreed a proposal which would have allowed Brexit talks to move onto the second phase, but the DUP, which props up Mrs May's minority government, was unhappy at the prospect of being offered a different EU deal to the rest of the UK.

And now the proposed Brexit deal has been thrown into turmoil with critics accusing the Government of putting the historic Good Friday Agreement at risk amid fears a hard border could plunge the region into another 30 years of violence.

Speaking on the Irish border issue in the House of Commons this afternoon, Ken Clarke described the Government's policy as "slightly ludicrous".

He said during his speech: "The Government keeps saying its committed to an open border, absolutely right consistent with the Good Friday Agreement, then says we're leaving the single market and we're leaving the customs union.

"I have said before, said it many times they are at complete contradiction it seemed to me completely incompatible. The two together are an oxymoron.

"I thought at last the light dawned when the Prime Minister moved in her discussion with the Taoiseach and reached an agreement.

"No doubt she believed she would get the approval of this House for regulatory convergence in certain areas at least across the border.

"I took that to mean the whole United Kingdom because we can't have separate arrangements in Ireland, so at last common sense is dawning, because whatever you call it you can't have any trade agreement with any other country in modern times unless actually you've agreed to mutually binding arrangements for regulatory and customs convergence."

Mr Clarke added he hoped the breakdown between the Government and the DUP over this agreement was down to "sheer incompetence".

Speaking on day five of the European Union (Withdrawal) Bill's committee stage debate, he backed a motion from independent MP Lady Hermon who appealed for the government to preserve the principles of the Good Friday Agreement in the legislation.

And the Conservative former cabinet minister Mr Clarke challenged the DUP to confirm further details about why they objected to a proposal for post-Brexit border arrangements.

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He said: "The DUP could always actually rescue their reputation if they confirm that their only objection was not having regulatory and customs convergence across the whole United Kingdom, and they were quite prepared to agree - as she and I would - that regulatory and customs convergence across the whole of the island of Ireland is certainly in the interests of inhabitants of both sides of the border."

Lady Hermon described it as a "very interesting" intervention, but said the DUP would have to speak for themselves.

However Robin Walker, the Brexit minister, went on to tell MPs that the Government will not accept Lady Hermon’s amendment.

He said the Government was strongly committed to the Good Friday Agreement, but could not accept the amendment for technical reasons. 

Lady Hermon said she was disappointed but Mr Clarke, however, lashed out at the failure.

He said if the Government wanted to improved the wording of the amendment, it could.

And he added several MPs say if Government MPs vote against the amendment, it will look as if they are voting against the Good Friday Agreement.