Doctors and radiographers in the city's west have warned patients' lives are at risk unless a 24-hour hospital is built in Melton by 2022.

Thirty-three GPs, cardiologists and radiographers have signed a letter imploring both state and federal governments to commit to fully funding a major public hospital in Melbourne’s fastest growing area.

"Due to inadequate access to hospitals, prolonged transfer times and extended waits in emergency departments, avoidable deaths of patients are now becoming a regular occurrence in the district of Melton," the letter reads.

"Why is Melton being neglected when all comparable population centres in Victoria have hospitals with 24-hour emergency departments, operating theatres, acute beds and psychiatric facilities?"