Negotiators from the European Union and Britain on Monday hailed major progress in the Brexit talks, but conceded there had been no breakthrough on keeping open the Irish border.

Britain is due to leave the European Union at the end of March 2019, but Brexit talks must be concluded by this fall to leave national parliaments in the bloc time to ratify any deal.

"We have travelled a large section of the path toward an orderly withdrawal," EU chief negotiator Michel Barnier told reporters in Brussels. He said that negotiators, working day and night recently, had agreed on "a large part of what would constitute" the draft legal treaty governing Britain's departure.

He said the two sides have also reached an agreement on a transition period to help ease Britain out of the EU once it officially leaves on March 29, 2019. Barnier said the period would be "of a limited duration," in all likelihood ending on Dec. 31, 2020.

Alongside him, British envoy David Davis said the progress made is a "significant step" toward a final deal.

Davis said he is confident that the draft legal text the sides have prepared will be endorsed by European Union leaders when they meet on Thursday and Friday.

Barnier said Britain must continue to respect EU laws and would continue to benefit from Europe's single market and customs union during the transition period.

Davis said international agreements would continue to apply to Britain now and during the transition period after Brexit takes place in 2019. He said the two sides had agreed to set up a joint committee to resolve any disputes during that transition.

"We must seize the moment and carry forward the momentum of the last few weeks," Davis said.

Both sides agreed to intensify talks to keep open the border between Ireland, which is an EU member, and Northern Ireland, which is part of the U.K.

In Berlin, meanwhile, a group representing European carmakers urged the Brexit negotiators to urgently address issues affecting the auto industry and to prevent "potentially disastrous implications" for its supply chain.

The European Automobile Manufacturers' Association, or ACEA, said it's concerned about whether cars approved by U.K. authorities can still be sold in the EU after Brexit and vice versa. It called for both sides to recognize each other's vehicle approvals.

It also said any new customs checks "would add cost, cause delays and threaten productivity."