The European Union`s chief Brexit negotiator warned ministers from the other 27 member states on Monday that no deal has been sealed on Britain`s departure from the bloc. "Michel Barnier explained that intense negotiating efforts continue, but an agreement has not been reached yet," the European Council, which represents the member states, said in a statement. "Some key issues remain under discussion, in particular a solution to avoid a hard border between Ireland and Northern Ireland." EU ministers voiced caution Monday about the chances of striking a rapid Brexit deal, at the start of another week billed as crucial for an agreement. Ministers from the other 27 member states were to be briefed by EU chief negotiator Michel Barnier as time runs down before Britain`s withdrawal on March 29. "We have time but not so much," Belgian Foreign Minister Didier Reynders told reporters as he arrived for talks with fellow EU ministers in Brussels. "It`s difficult to make real progress, but before Christmas I`m hoping it`s possible," Reynders said, as the EU awaits a "positive signal" from London.