Sir Keir Starmer is self-isolating after a member of his private office staff tested positive for coronavirus.
A spokesman for the Labour leader said that he had not shown any symptoms of the disease but would be working from home in line with Government regulations.
"This afternoon, Keir Starmer was advised to self-isolate after a member of his private office staff tested positive for the coronavirus," the spokesman said.
"Keir is well and not showing any symptoms. He will now be working from home."
It is understood Sir Keir will stay at home until December 16 – 14 days after he last came into contact with the staff member concerned last Tuesday.
This is the second time that he has been required to self-isolate.
In September Sir Keir went into quarantine when one of his children developed possible symptoms of the disease only for a test to come back negative two days later.