Senior Constable Holland, a police association delegate for the district, says police will be called to each and every incident because the guards will have very limited powers.

"As a Frankston resident and ratepayer I don't want to pay for what should be provided by the Government from my taxes," Senior Constable Holland told last week's special council meeting.

He said Frankston police were "stretched and under the pump" and attending to more incidents due to the security guards would put further pressure on police.

The union says research it commissioned from the National Institute of Economic and Industry Research shows Frankston needs a further 111 officers and 31 more for the peninsula.

The council ignored Senior Constable Holland's pleas and voted 7-2 in favour of trialling the private security guards. This has put it on a collision course with the Government, which is battling Opposition claims it has dropped the ball on law and order.

Following the decision, Frankston's Superintendent Wayne Taylor moved to hose down fears about police numbers in Frankston, saying the area would get a further 20 officers when the Carrum Downs station was built.

However police union secretary Senior Sergeant Greg Davies said not enough police were being employed to cope with Victoria's expanding population.

"The numbers of police in Frankston has dropped by 20 per cent in the past seven years, while Victoria's population now increases by about 1400 people per week," Mr Davies said.

"The Government has increased police numbers by 1400 in the past decade.

"Security guards do not have statutory or common law police powers, including the power to arrest. They can never provide a policing service.

"It is outrageous that the State Government continues to neglect our police force to the point where we are seeing these sorts of 'local sheriff's departments' being created by councils. It should never have to happen."