BORIS Johnson has rowed back on leaked UK plans for a Brexit deal based on limited border infrastructure in Ireland after it was dismissed out of hand by politicians on the island.

Irish deputy premier Simon Conveney called it a “non-starter”.

EU officials were also reported to be dismayed by the Government's suggestion there could be custom posts a few miles either side of the Irish border, rather than directly along it.

The proposal, floated in a “non-legal” discussion paper, comes ahead of Mr Johnson putting a final, legally operative text before EU leaders later this week, after the Tory conference.

The Irish broadcaster RTE reported the latest paper proposed “customs clearance zones” in Northern Ireland and the Irish Republic set back from the border.

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Although this would technically avoid a hard border, it would still create infrastructure nearby that could become a target for paramilitaries, jeopardising the peace process.

On BBC Radio 4’s Today programme, Mr Johnson said the leaks were “not quite right”, then said he was “absolutely not” proposing customs posts of the sort in the non-paper.

However he accepted that more border checks of some sort were part of his thinking.

Mr Coveney tweeted: “Non-Paper = Non-Starter. Time the EU had a serious proposal from the UK Govt if a #Brexit deal is to be achievable in October. NI and IRE deserves better!"

Sinn Fein leader Mary Lou McDonald said the leaked proposals to change the backstop put forward by the UK over Brexit were "essentially" a return to a hard border in Ireland.

Asked whether she could back such draft plans, she said: "Absolutely not."

The Irish politician said: "What has been described in this document is essentially a hard border on the island of Ireland. Anything that causes there to be customs, tariffs, checks anywhere represents a hardening of the border."

She also said any changes to the Irish backstop proposal agreed with the EU under Theresa May amounted to a "sabotage" of the peace process in Northern Ireland.

She said: “We have explained this in painstaking detail to Mrs May in her time and now Prime Minister Boris Johnson.

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"Privately both always said that they understood that and therefore it is all the more disgraceful that they would try and sabotage the peaceful dispensation on our island.

"Boris Johnson voted for the backstop because in a moment of perhaps rare lucidity he recognised that was the bottom line to protect the island of Ireland.

“I only hope he returns to that position."

An Irish government spokesman said a credible alternative to the backstop had yet to be proposed by the UK.

"The EU task force has indicated that any non-papers it has received from the UK to date fall well short of the agreed aims and objectives of the backstop," he said.

"The UKs non-papers were given to the task force on the strict understanding they would not be shared with anyone.

"The task force has said it has received no credible proposals from the British.

"Ireland's priorities are protecting the Good Friday Agreement, avoiding a hard border and protecting the all-island economy, and protecting the EU single market and its benefits for Irish businesses and consumers.

"We have yet to see any credible alternatives to the backstop."

LibDem leader Jo Swinson said the idea showed Mr Johnson was “not serious” about a deal.

"He knows that this is going to be rejected," she told BBC Radio 4.

Ms Swinson also said cross-party talks continued about how to ensure the Benn Act was "watertight".

She raised concerns that although Mr Johnson has promised to respect the rule of law, he has also promised to deliver Brexit on 31 October, with or without a deal.

"Those two things can't simultaneously be true," she said.