The EU’s chief negotiator, Michel Barnier, will update the bloc on the state of the negotiations later when he briefs EU commissioners and ambassadors.
Mr Johnson is facing a race against the clock to reach a new Brexit deal before the two-day gathering of EU leaders.
Any deal will need to be published – along with a legal text – if the EU27 are to consider ratifying the withdrawal agreement at their summit.
The UK is due to leave the EU at 23:00 GMT on 31 October and the prime minister has repeatedly insisted he will not request a delay.