Boris Johnson will fly to Brussels later for talks on a post-Brexit deal with the European Commission President Ursula von der Leyen. Time is running out to reach a deal before 31 December, when the UK stops following EU trading rules. The pair will hold talks over dinner, after negotiations between officials ended in deadlock. Major disagreements remain on fishing rights, business competition rules and how a deal will be policed. At the dinner, expected to begin at 19:00 GMT, the prime minister will work through a list of the major sticking points with Mrs von der Leyen, who is representing the leaders of the 27 EU nations. A UK government source said progress at a political level may allow the negotiations - between the UK's Lord Frost and EU's Michel Barnier - to resume over the coming days. But the source added that it was important to be "realistic" that an agreement might not be possible. Speaking at Prime Minister's Questions, Mr Johnson said "a good deal is still there to be done", but stressed that the EU's position was to have an "automatic right to punish us" if the UK's rules and regulations didn't move in step with the EU in the future. Meanwhile German Chancellor Angela Merkel has said a Brexit deal was still possible but insisted that the integrity of the EU single market must be respected. EU sources told the AFP that Mr Barnier briefed the bloc's Europe ministers that talks were tilting towards no deal being reached before the deadline. AFP political editor Laura Kuenssberg says that the purpose of the dinner is not to call a halt or to proclaim that a deal's been done. "The reason for the meeting is to see if both sides are willing in principle to tolerate the notion of budging, after the negotiations, and frankly negotiators, have been exhausted," she says. EU leaders are due to meet for a summit of their own on Thursday.