Security arrangements have come under fire after a public servant was bitten and mugged at a government office in Victoria.

An intruder reportedly carried out the vicious attack on a female worker at a CBD office tower last Thursday, after following her back from a nearby ATM.

Authorities say the man followed the woman, aged in her 30s, into a secure office at 1 Spring Street, which houses the Department of Economic Development, Jobs, Transport and Resources as well as the Department of Environment, Land, Water and Planning and where she worked for the local government department.

He tackled the woman the floor before biting her and stealing her purse.

Fellow office workers were able to restrain the man and hand him over to the building’s security guards, private security firm G4S, but he was then able to escape.

Reports say the perpetrator disappeared while the G4S security staff were photocopying his identification.

One office worker told Fairfax Media that the security guards were “useless”, though they did manage to hand a copy of the I.D over to police.

There are claims that the security staff been told to remain extra vigilant and check the identification of everyone entering the building.

But Community and Public Sector Union Victorian secretary Karen Batt says she was not approached by any security staff or asked for documentation when she attended a meeting at the same office tower just days later.

Ms Batt told Fairfax that security at government offices in nearby Southern Cross Tower required visitors to provide photo identification in order access the lift wells.

“That doesn't happen at 1 Spring Street. They're relying on staff simply walking in with a staff lanyard and they've got private security that are supposed to look at it.”

A government spokesperson said changes would be made.

“The department takes the safety of staff extremely seriously and we are working with the building managers to review security infrastructure and processes to help ensure such an incident doesn't happen again,” she said.