Seven teenagers have been arrested for impersonating police in eastern Victoria.

An off-duty policewoman was driving along the Princes Freeway near Traralgon, in Gippsland, last Friday when a car came up behind her with flashing red and blue lights.

The officer pulled over but became suspicious and tried to drive off.

A second car blocked her in, but both fled when she identified herself as a police officer.

Seven boys aged between 16 and 18 have been arrested.

They will be charged on summons.