LONDON, July 5 (Reuters) - Private equity company Apollo Global Management is in the preliminary stages of evaluating a possible offer for British supermarket group Morrisons, it said on Monday.

On Saturday Morrisons agreed to a takeover led by SoftBank owned Fortress Investment Group that valued Britain's fourth-largest grocer at 6.3 billion pounds ($8.7 billion) and topped a rival offer from another private equity firm Clayton, Dubilier & Rice (CD&R). (Reporting by James Davey; Editing by Kate Holton)