The European Union's Brexit negotiator Michel Barnier told a forum in Slovenia on Monday that a divorce deal with Britain could be agreed in six to eight weeks if negotiators are realistic in their demands.

European Union's chief Brexit negotiator Michel Barnier

Ljubljana:

"I think that if we are realistic, we are able to reach an agreement on the first stage of the negotiation, which is the Brexit treaty, within six or eight weeks," Barnier told the Bled Strategic Forum when asked by an interviewer.

"Taking into account the time necessary for the ratification process, the House of Commons on one side, the European Parliament and the Council on the other side ... we must reach an agreement before the beginning of November.

"I think it is possible."

Although Barnier was cautious and stressed that differences on the Irish border issue remain a serious sticking point, sterling jumped to a five-week high of $1.3052 on the report, up around 1 percent on the day, and rose around 0.3 percent against the euro.

Barnier has regularly said that he wants a deal by November to ensure parliamentary ratification by March, when Britain must leave, with or without a deal. He has routinely said that this timetable is a realistic one if negotiators find compromises.

He stressed that he and the EU were "determined" to reach a deal, but said he was neither optimistic nor pessimistic.

He declined to be drawn into arguments within the British government over Prime Minister Theresa May's proposals for a close arrangement on customs and regulations for goods trade, describing them with a smile as an "intense, stimulating debate".