London (AFP)

Negotiations between the UK and the EU on their post-Brexit relationship resume Monday in London, with the hope of overcoming the significant "differences" highlighted on both sides, despite the little time remaining.

"Glad to be back in London today, we are redoubling our efforts to reach an agreement on the future," EU negotiator Michel Barnier tweeted on Monday morning.

He identified three "keys" to unlock the negotiations, including "respect for EU autonomy and British sovereignty".

He also stressed the need for "strong guarantees of free and fair trade and competition" and "stable and reciprocal access to markets and fishing opportunities for the benefit of both parties".

European Commission President Ursula von der Leyen and British Prime Minister Boris Johnson took stock of the talks on Saturday.

"Some progress has been made, but major differences remain", in particular on fisheries and the guarantees that the EU is demanding in terms of competition, Ms von der Leyen underlined on Twitter.

- "Reasonable approach" -

The British government could show flexibility on fishing, hinted Monday the Minister of the Environment, George Eustice.

“When it comes to fisheries, we've always been willing to take a reasonable approach, looking in particular at agreements that could cover two, three years for example,” he told SkyNews.

Time is running out, with mid-November being considered the deadline in order to be able to ratify an agreement in time for it to enter into force on January 1, 2021, at the end of the transition period.

The UK left the EU on January 31, but continues to apply EU rules until December 31, a transition period allowing London and Brussels to negotiate an agreement on their future trade relationship.

In the absence of an agreement, a sudden break in trade would further shake up economies already weakened by the new coronavirus pandemic.

In this tense context, a British bill calling into question certain commitments made by London in the treaty governing his departure from the EU is being considered in the House of Lords, where parliamentarians are expected to inflict a setback on Boris Johnson.

For Mr Johnson, the aim of the project is to defend the territorial integrity of the United Kingdom by ensuring the continuity of trade between Great Britain and the province of Northern Ireland.

But the European Union notes that this text is a violation of the Brexit treaty.

This subject risks being a source of disagreement between US President-elect Joe Biden and Britain's conservative leader, as London seeks to negotiate an ambitious trade deal with Washington.

"We cannot allow the Good Friday agreement, which brought peace to Northern Ireland, to become a victim of Brexit," Joe Biden warned in September, who proudly displays his Irish roots.

"If the government seriously plans to restart relations with the United States, it should take a first step and abandon these proposals," Keir Starmer, leader of the opposition Labor Party, pleaded Monday in The Guardian newspaper.

In this final stretch of negotiations, the election of Joe Biden will "maybe" make the difference, Irish foreign minister Simon Coveney told Irish public radio RTE.

It will "give Downing Street food for thought to make Irish issues the priority as we try to conclude this phase of the Brexit negotiations".

© 2020 AFP