Investigators don't know how bikies got hold of several police uniforms.

Investigators don't know how bikies got hold of several police uniforms. Photo: Paul Rovere

Victoria Police uniforms and a machinegun were seized in a raid against outlaw motorcycle gang members on Thursday, police say. 

Investigators searched four houses in Melbourne's east and south-east from 5am and arrested three men and a woman, a Victoria Police spokeswoman said. 

She said the operation was to disrupt criminal activities conducted by the Mongols Outlaw Motorcycle Gang.

Investigators were yet to determine how the alleged gang members came into possession of the genuine police uniforms, the spokeswoman said.  

 

Ammunition, drugs and prohibited weapons were also seized. 

A 29-year-old man and a 24-year-old woman from Bentleigh East, a 26-year-old man from Narre Warren and a 29-year-old Carnegie man were arrested and are expected to be charged on Thursday afternoon. 

The properties were in Normanby Road, Bentleigh East; Neerim Road, Carnegie; Oaks Grove Drive, Narre Warren; and Grandview Grove, Bayswater.