A return of border checks between Northern Ireland and the Republic appears inevitable after Britain leaves the EU, MPs have warned.

The Commons Exiting the EU Committee said it appeared impossible to reconcile the British government's decision to pull out of the single market and the customs union with its declared intention to maintain a "frictionless" border.

It said the government's proposals for dealing with the issue, including using technology to create a "light touch" border, were "untested and to some extent speculative".

Brexit: Border 'deal' in tatters after DUP threatens to withdraw support from May

"We do not currently see how it will be possible to reconcile there being no border with the government's policy of leaving the single market and the customs union, which will inevitably make the border between Northern Ireland and the Republic of Ireland the EU's customs border with the UK," the committee said.

But the report split the committee with four of the eight Conservatives present as well as the lone DUP member voting to reject it.

Yesterday, East Antrim MP Sammy Wilson said any attempt to "placate Dublin and the EU" by allowing Northern Ireland to have different customs rules from Britain would jeopardise the agreement to prop up the Tories.

Sinn Féin vice-president Mary Lou McDonald also claimed the plan "misses the point" and insisted special status within the EU was the only solution.

Former leader Peter Robinson also joined attacks on the Irish government, saying "the south needs to wind its neck in".

The findings of the Commons Exiting the EU Committee echo the concerns of the Irish government which has demanded a written guarantee from the UK that there will be no return to the "hard border" of the past as a result of Brexit.

Taoiseach Leo Varadkar has warned that without such an assurance, EU leaders will not give the green light for the second phase of the Brexit negotiations, including talks on a free trade deal, to begin at their summit on December 14 and 15.

In its report, the committee urged the British government to begin work on ensuring the flow of goods in and out of the UK continued as freely as possible, regardless of whether there was a deal, including installing electronic customs checks and the construction of a lorry park at the Port of Dover.

But it added: "Such measures would not deal with all the risks of serious delays in Dover and would have to be reciprocated across the Channel in order to be effective."

The report also called on ministers to publish a white paper explaining how its proposed two-year transition period after the UK leaves the EU in March 2019 would work in practice.

It said any agreement between the UK and the EU on future citizens' right should be "ring-fenced" to ensure the status of EU nationals living in the UK and British nationals in the EU was guaranteed regardless of whether there was a wider deal.

One of the four Tory Brexiteers who voted against the report, Craig Mackinlay rejected the suggestion that leaving the single market and the customs union would mean bringing back a "physical border infrastructure" between the north and the Republic.

"Of course, there has long been a VAT and currency border. Goods and services entailing cross-border transactions have paperwork and electronic filing to efficiently and effectively handle the different tax regimes," he said.

"If we end up with the World Trade Organisation model, for instance, I see no reason why it is not possible to add a customs tariff, if necessary under a no-deal scenario."

The cross-party committee's chairman, Labour MP Hilary Benn, told BBC Radio 4's Today programme: "Ministers say they don't want a border, they don't want any infrastructure. We all agree with that, but we didn't see, as a committee, how currently that can be reconciled with the Government's decision to leave the customs union and the single market.

"We call on the government to set out more clearly how it is it thinks that this can work in practice, because it published its paper, which talks about two options - a highly streamlined customs arrangement ... a new customs arrangement with the European Union.

"It admits that its proposals are untested and at the moment it's not clear how this might work. But this is of fundamental importance."

He added: "Self-evidently, the Irish government is not persuaded by what it has read so far."

Mr Benn said the committee continued to seek the full, unedited versions of Department for Exiting the EU analyses of the impact of Brexit on different sectors of the economy, which were handed over in redacted form earlier this week.

"That is what the House of Commons asked for," he told Today. "It said the material should be given to the Brexit select committee. It didn't say that the material should be edited or filleted in any way.

"It should be passed over and it should be the job of the committee - that's what we think - to decide what should be published."

Dublin foreign minister Simon Coveney said Dublin was not willing to "leap into the dark" by accepting a move to the second phase of Brexit negotiations on the basis of vague assurances the border will be kept open.

He said in talks with Britain ahead of the December 14 summit, the Dublin government wants to secure "an agreed wording whereby we can agree the parameters within which we can find a solution that prevents the re-emergence of the border on the island of Ireland and all the negative consequences that flow from that".

"We believe it's possible to do that," he told the Today programme. "The area that we've focused in on is the need to give reassurance that there will not be regulatory divergence between the two jurisdictions on the island of Ireland, because if there is, then it is very hard to avoid a checking system.

"If you have different standards in terms of food safety, animal welfare, animal health, if you have different standards in relation to medical devices and the approval of drugs, how then can you maintain practical north/south co-operation as we have it today, if that regulatory divergence appears after Northern Ireland and the rest of the UK leaves the European Union."

Mr Coveney said the British government was "essentially saying 'We will solve this problem, but not just now"'.

But he said the reason why the Irish border issue was included in the first part of negotiations, alongside the UK's financial settlement and EU citizens' rights, was precisely "so that we can give reassurance in phase one that these problems can be solved in phase two".

He said: "What the British government has been asking of the Irish Government is to just 'trust us, we'll solve these issues with a broad, bold trade agreement'.

"But that may not be possible, we don't know. We can't be asked to leap into the dark by opening up phase two discussions in the hope that these issues might be resolved."

Former first minister Lord Trimble said Mr Coveney should "go back and rethink what he's saying".

"We are going to leave the EU and one of the reasons for leaving it is to have our own say no what the regulatory framework for British industry is to be," the Conservative peer told Today.

"He is saying we should continue to be bound in all circumstances by the EU regulatory framework. What would then be the point of leaving?"

Lord Trimble said he backed a British government proposal to avoid the need for border checks by exempting smaller companies from tariffs when moving goods between Northern Ireland and the Republic.

The Republic should ask Brussels to change EU law to relieve it of "the obligation to put infrastructure on the Irish side of the border", he said.

Liberal Democrat Brexit spokesman Tom Brake said: "The government has failed to convince anyone that a frictionless border solution exists. And they have ruled out the obvious answer, which is remaining in the single market and customs union.

"Their ideological obsession with a hard Brexit is putting 20 years of peace at risk. Only the Lib Dems are offering a chance to exit from Brexit and to maintain the peaceful status quo that currently exists in Northern Ireland."