British Prime Minister Boris Johnson tests positive for coronavirus.

British Prime Minister Boris Johnson has tested positive for the novel coronavirus.

Johnson’s office says he was tested after showing mild symptoms.

Downing Street says Johnson, 55, is self-isolating and continuing to lead the country’s response to COVID-19.

WATCH: All your COVID-10 questions, answered. Post continues after video.

“After experiencing mild symptoms yesterday, the Prime Minister was tested for coronavirus on the personal advice of England’s Chief Medical Officer, Professor Chris Whitty. The test was carried out in No 10 by NHS staff and the result of the test was positive,” a spokesperson said.

“In keeping with the guidance, the Prime Minister is self-isolating in Downing Street. He is continuing to lead the government’s response to coronavirus.”

Johnson announced the news on social media on Friday night.

“Over the last 24 hours I have developed mild symptoms and tested positive for coronavirus,” he said.

“I am now self-isolating, but I will continue to lead the government’s response via video-conference as we fight this virus.”

Over the last 24 hours I have developed mild symptoms and tested positive for coronavirus.

I am now self-isolating, but I will continue to lead the government’s response via video-conference as we fight this virus.

Together we will beat this. #StayHomeSaveLives pic.twitter.com/9Te6aFP0Ri

— Boris Johnson #StayHomeSaveLives (@BorisJohnson) March 27, 2020

It was not immediately clear how many Downing Street staff and senior ministers would now need to isolate given that many have had contact with Johnson over recent days and weeks.

When Britain clapped health workers on Thursday evening, Johnson and his finance minister Rishi Sunak came out of separate entrances on Downing Street and did not come into close contact, according to a Reuters photographer at the scene.

Previously the government has said that Johnson had the option to delegate to Foreign Secretary Dominic Raab if needed.

“The prime minister was tested for coronavirus on the personal advice of England’s Chief Medical Officer, Professor Chris Whitty,” the spokesman said.

“The test was carried out in No 10 by NHS staff and the result of the test was positive,” the spokesman said.

So far, 578 people in the United Kingdom have died after testing positive for coronavirus and the number of confirmed cases has risen to 11,658. The UK toll is the seventh worst in the world, after Italy, Spain, China, Iran, France and the United States, according to a Reuters tally.

Britain’s Prince Charles, the 71-year-old heir to the British throne, tested positive for coronavirus earlier this week but is in good health and is now self-isolating at his residence in Scotland with mild symptoms along with his wife Camilla, who tested negative, his office said.

On Monday, the Prime Minister issued a lockdown for the UK, banning people from leaving their homes apart from a few ‘limited’ reasons.

– With AAP.