The RAAF wants to close bases at Richmond in western Sydney and Laverton outside Melbourne in a move that could shift hundreds of defence personnel to other states but free up large tracts of land for development.

The Chief of Air Force, Air Marshal Leo Davies, said on Thursday the RAAF had a preference for Richmond and Laverton to close, though he stressed this was part of a broader plan that had not yet been put to the government.

Defence Minister Marise Payne said the government was "not considering" closing either base despite the RAAF's signalling that Richmond in particular will need heavy investment to make it worthwhile keeping it open.

Air Marshal Davies said Richmond's functions had been diminishing for years and a decision was needed on whether to close it or invest hundreds of millions of dollars to get it to a "fighting state".