Bathurst police have launched an investigation following fears a series of forged medical certificates could be circulating in the community.

Authorities are warning employers to report any suspicious documents, following a tip-off from a local doctor's surgery.

Dr Anne Gilroy's, Westpoint Medical Centre has been at the centre of allegations her practice willingly hands out medical certificates to cover patients for sick leave.

So the Bathurst GP wasn't surprised when she received a phone call from one of the city's largest employers, after it discovered multiple photocopies of altered medical certificates from Westpoint.

The matter has now been placed into the hands of local police, who insist forging a medical certificate is a criminal offence.