UK PM Boris Johnson in intensive care with COVID-19

British Prime Minister Boris Johnson is in intensive care, days after testing positive for coronavirus.

The news comes just hours after he was admitted to hospital for tests, 10 days after being diagnosed.

In a statement released announcing the premier's hospitalisation, Downing Street said it was a "precautionary step" and not an emergency admission. 

Housing minister Robert Jenrick confirmed on Monday, that Johnson would continue to lead the government, despite having spent the night in the hospital for tests. 

On 27 March, Johnson became the first leader of a major power to announce that he had tested positive. He went into isolation at a flat in Downing Street and said on Friday that he was staying there as he still had a high temperature.

Johnson has continued to chair daily meetings on the UK's response to the outbreak and has released several video messages during his 10 days in isolation.

"Since Sunday evening, the prime minister has been under the care of doctors at St Thomas' Hospital, in London, after being admitted with persistent symptoms of coronavirus," Johnson's office said.

"Over the course of this afternoon, the condition of the prime minister has worsened and, on the advice of his medical team, he has been moved to the intensive care unit at the hospital...The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication."

Johnson is reportedly conscious and not on a ventilator, although one was available.

UK foreign secretary Dominic Raab is temporarily acting Prime Minister.