Victoria Police has complained to Facebook, saying a page dedicated to exposing the state's undercover police cars is putting officers and operations at risk.

The page has more than 12,500 followers and has dozens of photos and comments revealing the number-plates of unmarked police cars.

A News Limited report says Facebook has refused a police request to remove the page, saying it cannot stop people taking photos in public places.

Victoria Police says it takes the safety of its members seriously and is monitoring activity on the page.

But Police Association Secretary Greg Davies says the state's criminal element is bound to be keeping tabs on it too.

"Not every criminal in Victoria is a moron," he said.

"This is available for anybody to have a look at.

"It is effectively a database of as many, what people believe to be unmarked police vehicles and operations as they can gather, so it's a pretty good resource for them."

Mr Davies says it is irresponsible for Facebook to retain a page which publishes photos of unmarked police cars.

"Facebook is a creature of the 21st century, it's time it stepped into the responsibilities of the 21st century," he said.

"This could jeopardise not only ongoing police operations, but it could jeopardise police officers as well.

"Facebook has to show some responsibility and take this thing down."