“Prince Albert is continuing to work from the office in his private apartments,” it said in a statement.

The office also added that Prince Albert is in constant contact with members of his cabinet, the government and his closest staff.

The European Union’s chief negotiator for Brexit, Michel Barnier, also said on Thursday he had tested positive for coronavirus.

The virus has infected almost 219,000 people across the world and the death toll has exceeded 8900.

Prince Albert’s diagnosis comes as another monarch, Queen Elizabeth, said the royal family will play its part as Britain rises to the challenge of overcoming the coronavirus pandemic.

“Many of us will need to find new ways of staying in touch with each other and making sure that loved ones are safe. I am certain we are up to that challenge,” the 93-year-old monarch said in a message to the nation.

“You can be assured that my family and I stand ready to play our part.”

On Tuesday, the queen announced she had cancelled her annual garden parties and several other events, and would head to Windsor Castle, west of London, on Thursday with her 98-year-old husband Prince Philip for Easter – a week earlier than usual.

Buckingham Palace said the changes were “a sensible precaution”.

The queen’s message went on: “As Philip and I arrive at Windsor today, we know that many individuals and families across the United Kingdom, and around the world, are entering a period of great concern and uncertainty.

“We are all being advised to change our normal routines and regular patterns of life for the greater good of the communities we live in and, in particular, to protect the most vulnerable within them.

“At times such as these, I am reminded that our nation’s history has been forged by people and communities coming together to work as one, concentrating our combined efforts with a focus on the common goal.”

She added: “We are enormously thankful for the expertise and commitment of our scientists, medical practitioners and emergency and public services; but now more than any time in our recent past, we all have a vitally important part to play as individuals – today and in the coming days, weeks and months.”

– AAP