The European Union still expects to conclude talks on a post-Brexit fishing rights row with Britain on Friday, a spokeswoman said, despite London saying it does not recognise the deadline.
"Where we are is that on both sides, on the European Commission and UK, we have agreed that we have this mutual commitment to end these discussions for the successful outcome Friday," Vivian Loonela said.
Talks are underway between the UK and the commission on the remaining fishing licences yet to be accorded to French boats operating in British and Channel Island waters after Brexit.
A furious France has threatened to make a legal complant if the matter is not resolved by midnight on Friday, although Britain has said it does not recognise the deadline.
Briefing journalists in Brussels, the commission spokeswoman said the European Commission does not use the term "ultimatum" but understands that UK negotiators plan to resolve the dispute in the coming hours.
French officials have said that they will demand the European Commission activate a complaint mechanism in the post Brexit "Partnership Council" and pursue binding arbitration if the deadline is missed.
British Environment Secretary George Eustice is holding talks EU Environment Commissioner Virginijus Sinkevicius, and some progress has been made.
The Channel Island of Jersey has accorded 10 licences to French boats, and Guernsey 43, she said.
But France says that 104 of its boats lack permission to fish in Jersey waters, while UK and EU officials scour logbooks dating from 2012 to 2016 to confirm that they have traditionally done so.