Bestiality accused flashed dog's owner

A man has allegedly tried to commit bestiality on a dog after assaulting it and flashing its owner in Sydney's west.

The man was riding a pushbike through Greystanes on Sunday afternoon and approached two women, 20 and 23, as they walked their dogs, police say.

He allegedly then assaulted one of the dogs, exposed himself and tried to commit bestiality on the other.

The women fled and contacted police, who saw a man fitting his description in the same area on Monday morning.

He ran from police and after a short chase PolAir and the dog squad were called in, but the man wasn't found.

The search for the man continues and police have asked for anyone with information to come forward.