Ursula von der Leyen, the president of the European Commission, wished the ill official a “speedy recovery” and said “work will continue in full respect of Covid-19 rules”.
A UK Government spokesman said: “The UK and EU teams have agreed to continue to negotiate remotely for the time being. The talks will resume in person when it is judged safe to do so.”
There is no need for anyone on the UK side to self-isolate. When face-to face talks can resume, it is expected that the negotiations will be in London.
Under Belgian law, anyone who has come into contact with someone who has tested positive for Covid must self-isolate. If someone has a negative test, the quarantine is cut to seven days.
Negotiations were conducted online after the pandemic first broke out in March. Face-to-face talks resumed in July after negotiators complained that online talks made it hard to reach difficult compromises.
EU diplomatic sources claim the trade deal is 90 per cent done but warn that crucial breakthroughs on fishing, “level playing field” guarantees and protocols around the deal’s enforcement remain elusive.
An UK-EU free trade agreement could be announced as early as Monday, a source predicted, if compromises are made.
News of the Covid case plunged the tight timetable for the agreement and ratification of the trade deal into disarray, but Brexit deadlines have a habit of being stretched.
A senior EU official warned that if the deal was not agreed by Monday there would not be enough time to translate the agreement into the EU’s other 23 official languages for ratification by the European Parliament.
MEPs must ratify the finalised agreement before the end of the year, otherwise the UK will trade with the EU on WTO no-deal terms from January 1.
A few more weeks could be bought if the decision was made to forego translation and simply ratify the deal in English, the official said. Diplomatic sources said that was likely to be resisted by France.
Senior EU diplomats have predicted that a “creative solution” could be found to ratify the deal beyond the end of the year if one could be agreed before December 31.
Mr Barnier, who told Mrs von der Leyen on Wednesday that the talks were in their “final push”, was set to brief EU ambassadors in Brussels on Friday. A deputy will now take the meeting.