UK Prime Minister Boris Johnson has confirmed that he has tested positive for coronavirus.

The deadly disease has so far infected more than half a million people and claimed almost 25,000 lives globally, while vast swathes of the population are isolating at home in a bid to avoid and slow the spread of COVID-19.

In a short video posted to Twitter, Johnson revealed that he has tested positive and is now self-isolating in 10 Downing Street as per government guidelines.

"Over the last 24 hours I have developed mild symptoms and tested positive for coronavirus," he wrote in the accompanying message. "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."

Many of Johnson's cabinet colleagues, including health secretary Matt Hancock and Chancellor of the Duchy of Lancaster Michael Gove, may now have to self-isolate too after coming into contact with the PM in recent days.

Foreign secretary Dominic Raab has been named as the "designated survivor" who will take over the running of the country should Johnson's condition deteriorate.