According to a report in the Financial Times talks between buyout specialist Clayton Dubilier & Rice and the two target FM businesses are at an early stage.
The aim would be to create a major FM business in the UK that was able to handle long term contracts for major clients.
Balfour Beatty WorkPlace turns over around £650m a year and employs 15,000 staff and contract workers.
Its clients include nine major hospitals, 200 schools, 500 government buildings and eight nuclear power stations.
In February, Balfour confirmed it was exploring options for the WorkPlace business in keeping with its strategy to focus on global infrastructure.
Industry experts believe the sale of Balfour Beatty WorkPlace could raise around £250m for the struggling group.
Likewise Rentokil said in March that it would consider selling its low-margin UK facilities management arm if an offer was forthcoming as it shifted its focus to building a stronger international businesses.
Rentokil’s FM arm, Initial Facilities Services, boasts a revenue of nearly £600m after growing through a series of acquisitions, which last year saw it buy Modus FM for £5m.
Rentokil, CD&R and Balfour Beatty declined to comment.