Greenwich Healthcare trust has been reported to the National Audit Office for allegedly misusing public money to develop a
local pay and job evaluation scheme.
The MSF union has registered a formal complaint with the NAO, arguing the scheme is likely to be overtaken by national policy.
MSF regional officer Gail Cartmail said: 'We cannot stand by and watch badly needed money being wasted on a scheme that might never see the light of day.'
MSF took advice from Lord Lester QC, an expert on equality in the workplace, who argued that any local job evaluation scheme is 'almost certainly challengeable on equal pay grounds'.
A national job evaluation working party is also discussing pay systems.
The trust denied it was spending money on developing local pay, but was 'purchasing a job evaluation scheme' to update its human resource practice and had 'consulted the local staff side on the matter'.