EU and British flags fly outside the European Commission building in London, Britain August 12, 2017. REUTERS/Neil Hall/File Photo

BRUSSELS (Reuters) - EU negotiators told national envoys on Friday that they need more work yet to close a Brexit deal with Britain, diplomats familiar with the briefing told Reuters.

One described the update on the state of play be members of European Commission negotiator Michel Barnier’s team as “sober” and free of “drama”. “More talks to be had,” summed up another.

Barnier’s deputy Sabine Weyand held further talks with Oliver Robbins, the lead negotiator for British Prime Minister Theresa May during the day, EU officials said, and more discussions were planned for Sunday, keeping up an intense pace.

Both sides have closed in on a deal but remain deadlocked over clauses aimed at avoiding disruption on the Irish border -- an issue that is dividing May’s government and jeopardizing her ability to get any agreement through the British parliament.

“The ball continues to be in the UK’s court,” said a third EU diplomat, stressing that the Union had already given London many options and that it needed now to make up its mind.

Britain is due to leave the European Union in March, with or without a deal to smooth the process which will separate the world’s fifth biggest economy from its biggest trading partners.