Melb man sought after sex act on trains

A man who exposed himself and performed sex acts in front of two women on Melbourne trains on two separate occasions is being sought by police.

The incidents occurred on trains in Oakleigh and Murrumbeena in March 24 and May 23 respectively, police said on Wednesday.

Investigators have released images of a man they believe can help with their inquiries and he is believed to be of Caucasian or southern European appearance with a thin build, black beard and was wearing a grey baseball cap, black jacket and black pants.