EU commission president Ursula von der Leyen on Thursday left a summit attended by the bloc's 27 leaders after learning that a staff member had tested positive for the coronavirus.

"I have just been informed that a member of my front office has tested positive to COVID-19 this morning," she said in a tweet.

"I myself have tested negative, however, as a precaution I am immediately leaving the European Council to go into self-isolation," she said, using the official term for the Brussels summit.