LONDON, June 20 (Reuters) - Britain's Observer newspaper said British Prime Minister Keir Starmer was expected ‌to resign on Monday and set out ‌a timetable for his departure, though a government source said Starmer ​remained focused on getting on with the job of governing.

The threat to Starmer's position, which has been building for months, increased sharply on Friday when his ‌rival Andy Burnham ⁠won a seat in parliament that would allow him to launch a formal ⁠leadership challenge.

The Observer report said Starmer was discussing the matter with his wife at his Chequers country ​residence before ​making a final decision, ​but that senior Labour ‌figures expected a clear statement on his future as early as Monday.

However, a government source said Starmer remained focused on his job and pointed to previous statements he has made to that effect.

The British ‌leader said on Friday he ​would fight any challenge to ​his position and ​urged Labour not to tear itself apart ‌with infighting.

More than 100 ​elected lawmakers in ​his party - roughly a quarter of all Labour representatives in the House of Commons - have ​publicly said they ‌want Starmer to quit or set out ​a timetable for his exit.

(Reporting by William James, ​Editing by Franklin Paul)