The European Union does not expect a Brexit breakthrough before the weekend, diplomats and officials said after talks in Brussels led by British Prime Minister Theresa May's chief lawyer failed to produce a deal on Tuesday.

"It's unlikely that there would be a deal before the weekend," one EU official said. "We are preparing for a working weekend."

Diplomats speculated that, should the EU and UK negotiators seal a deal over the weekend, May could come to Brussels on Monday to give it political endorsement and take it back to London just a day before the House of Commons votes on it.