EU chief negotiator Michel Barnier and his British counterparts have wrapped up the latest round of talks aimed at getting the Brexit deal through parliament in London.

Both sides are intensifying their talks this week on how to narrow the gap on meeting the UK's demand for legally binding guarantees on the backstop.

Prime Minister Theresa May is seeking legally binding changes to the backstop in order to persuade MPs that it is temporary, in the hope a majority will then support the Withdrawal Agreement.

Meanwhile, Tánaiste Simon Coveney has said that the EU will try to provide assurances that Britain would not be trapped in the backstop against its will indefinitely. 

However, he repeated that the Withdrawal Agreement could not be redrafted and the need for a backstop could not be undermined. 

Mr Barnier met UK attorney general Geoffrey Cox and Brexit minister Stephen Barclay for four hours over dinner, an EU official told AFP following conciliatory signals from both sides.

The official could not confirm whether the talks would resume tomorrow when he said journalists would be briefed on the results of today's meeting.

Mr Barnier said on Saturday the European Union was ready to give further guarantees to help the Brexit deal it struck with Mrs May in November get through the British parliament.

He also suggested European leaders would be amenable to a short "technical" delay in Britain's departure from the bloc scheduled for 29 March, to give parliament time to formally ratify a final accord.

"We are determined to get a deal over the line and deliver on Brexit," Mr Barclay tweeted as he and Mr Cox, the government's top lawyer, departed for Brussels.

There was no immediate comment from Mr Barclay after the talks ended.

His small overture to Britain has raised some hopes that both sides can find a solution, including to the so-called "backstop" plan for the Irish border, a major sticking point for pro-Brexit MPs.

The two sides are at a "critical point" in these negotiations, a spokeswoman for Mrs May said earlier.

British Brexit Secretary Stephen Barclay

Mr Cox's presence is seen as central as he will ultimately offer a legal opinion on the Brexit deal and the backstop, that could determine whether key pro-Brexit lawmakers will approve the Withdrawal Agreement.

Earlier, Tánaiste Simon Coveney said that the EU will try to provide assurances that Britain would not be trapped in the backstop against its will indefinitely. 

However, he repeated that the Withdrawal Agreement could not be redrafted and the need for a backstop could not be undermined. 

EU and UK officials have been working on three separate strands.

The first relates to "guarantees" on the temporary nature of the backstop.

The second is the exploration of "alternative arrangements", taken to mean technological solutions, that might replace the backstop.

The third strand is how to adapt the non-binding Political Declaration, which sits alongside the Withdrawal Agreement and maps out the future relationship.

The overall objective, say officials, is to allow Mr Cox to change his legal advice, dating back to November last year, that the backstop could "trap" the UK in a permanent customs union with the EU indefinitely.

Several sources confirm that London has dropped its demand for a unilateral exit clause for the UK or an expiry date on the backstop.

Neither the British nor the EU side have exchanged detailed texts so far.

It is understood both sides believe the later the publication of a text, the better its chances of being accepted by the House of Commons.

However, the hardline European Research Group has assembled a panel of eight law experts, seven of whom are eurosceptic MPs, to test the new legal advice when it appears.

Read more:
Barnier casts doubt on whether UK can leave on schedule
Latest Brexit stories

There is much speculation as to the form and content of any changes that London manages to secure.

Some officials say there could be as many as four separate documents or texts making up the anticipated deal; other sources have downplayed such a scenario, saying it is too early in the process to speculate.

However, Mr Barnier suggested last weekend that there could be some kind of "interpretative" statement on the "guarantees" over the backstop.

It is thought such a document, known as a Joint Interpretative Statement, could simply build on a letter from Donald Tusk and Jean-Claude Juncker, respectively the European Council and Commission Presidents, to Mrs May in January, spelling out that the backstop was designed to be temporary.

Irish sources have advised caution on such a mechanism.

It is understood there could also be a joint text between the European Commission and the UK which addresses the "alternative arrangements" option.

Sources point out that paragraphs 140 and 141 of the Political Declaration, setting out the future trade relationship, already provide the framework for both sides to explore the option of technology as a way of solving the Irish border question, but only once the Withdrawal Agreement has been adopted.

Both sides are also looking at adapting the non-binding Political Declaration so that it provides Mrs May with further comfort that the future trade deal, which London believes will supersede the backstop, will be negotiated quickly.

British Attorney General Geoffrey Cox

It is believed the UK is seeking a separate text, or joint statement, beyond the Political Declaration that might spell out a greater role for the UK parliament in scrutinising the trade negotiations.

However, a number of sources have said Mr Barnier has reservations about such an arrangement, believing it to be cumbersome.

A further text could spell out how Westminster might follow new EU legislation on workers' rights and the environment. This would be purely for domestic consumption in the UK, as it would not involve any commitments by the EU.

With the British government having abandoned its demand for a unilateral exit clause or an expiry date, it is understood London is now focusing on an independent arbitration mechanism as a way to highlight Britain's ability to exit the backstop.

EU chief negotiator Michel Barnier

"It's something to sort out this week," says one senior official. "The idea that an arbitration panel will play a role in the process. I think that has indeed been debated, but what exactly it will entail has not been discussed in any detail."

Officials point out that the Withdrawal Agreement already contains provisions for binding dispute settlement and enforcement rules.

It is thought that EU negotiators are insisting that any arbitration process on the backstop would ultimately have to abide by the European Court of Justice's remit.

According to EU officials, any agreement that supersedes the backstop should bring about a scenario where no checks and controls are required on the Irish land border.

Sources say that, since such checks and controls are intrinsic to the EU's customs union and single market, then ultimately the European Court of Justice should be the final arbiter.

Sources suggest this is proving a delicate area of the talks.

"Obviously if we are talking about the interpretation of EU rules and the EU's customs code, then the ECJ needs to play a role, and that's one of the difficult issues," one source told RTÉ News.

Additional reporting Tony Connelly