EU chief negotiator Michel Barnier is planning to extend his visit to London until Wednesday amid careful optimism over the progress of post-Brexit trade talks with Britain, the Sunday Telegraph reported.
The European Union negotiating team had been due to return to Brussels on Sunday.
The paper said the British team would travel to Brussels on Thursday for more talks and that next Saturday had dramatically become the deadline to decide whether the two sides could reach a deal.
Britain and the EU have made good progress in talks on a last-minute trade deal that would stave off an explosive finale to the five-year-old Brexit crisis, but fishing remains the most significant sticking point.
Hopes for an agreement rose last week when Reuters reported that France is preparing its fishing industry for a smaller catch after Brexit.