Sir Keir Starmer is self-isolating after a member of his household started showing "possible symptoms of the coronavirus".
The household member has had a test, and the Labour leader will continue to quarantine "while awaiting the results of the test and further advice from medical professionals," a spokesman said.
The Labour leader had gone into the studio at LBC this morning, and the radio station has been made aware of the possible transmission risk.
Sir Keir shared a studio with host Nick Ferrari during the phone-in show.
A spokesman for Sir Keir said: "This morning Keir Starmer was advised to self-isolate after a member of his household showed possible symptoms of the coronavirus.
"The member of his household has now had a test. In line with NHS guidelines, Keir will self-isolate while awaiting the results of the test and further advice from medical professionals."
The Labour leader is not speaking during today's debate on the Internal Market Bill, when it is expected that a number of Conservative MPs will look to rebel against the Government.
It is not clear how this will affect his ability to take part in other debates such as PMQs. It is understood that Sir Keir is not displaying symptoms.