Portuguese Prime Minister Antonio Costa delivers a speech during the official inauguration of the ARCO Lisboa International Contemporary Art Fair in Lisbon, Portugal, on May 15, 2019. ARCO Lisboa will open to the general public from May 16 to 19. (Photo: Xinhua)

Portuguese Prime Minister Antonio Costa has been in self-quarantine following close contact with French President Emmanuel Macron, who had tested positive for COVID-19 earlier on Thursday.

Costa tested negative on Thursday. He will remain in "preventive prophylactic isolation" and do another test in the next few days, according to a statement from his office.

"The Prime Minister maintains all executive activity and the non-face-to-face work agenda," said the statement, adding he canceled his planned visit to Africa later this month.