British Prime Minister Boris Johnson has been admitted to hospital for tests after showing persistent symptoms of coronavirus 10 days after testing positive for the virus.

His office said it was a "precautionary step", not an emergency admission.

"On the advice of his doctor, the Prime Minister has tonight been admitted to hospital for tests," Downing Street said on Sunday.

"This is a precautionary step, as the Prime Minister continues to have persistent symptoms of coronavirus 10 days after testing positive for the virus."

On March 27, 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.

In a message on Friday, he said he was feeling better but still had a fever. Johnson remains in charge of the government, Downing Street said.