Hunt for alleged cyclist predator after sexual assaults in Sydney's west

A police hunt is underway for a man captured on CCTV footage, after two sexual assaults and an attempted armed robbery in Sydney's southwest over the last month.

Police are calling for public assistance in helping identifying the man who they believe can help with inquiries into the three incidents in the Bonnyrigg Heights and Mount Pritchard areas.

Police are looking for public assistance in identifying this man on a bicycle on November 4. Source: Facebook/NSW Police

The first incident involved a 14-year-old girl who was approached by a man on a bicycle in a reserve in Lalich Avenue, Bonnyrigg, on October 8 around 3.30pm before he indecently assaulted her.

Several weeks later, a 48-year-old woman was cycling through a park near Hamel Road, Mount Pritchard, on November 4 around 5pm when she was indecently assaulted by a man on a bicycle.

Police are urging for anyone with any information to come forward. Source: AAP

Shortly after 8pm on the same day, a man armed with a knife threatened a 14-year-old boy at the park before fleeing on a bicycle.

"It'd be extremely frightening and disturbing for the two young 14-year-old children who have been assaulted ... and also for the woman assaulted," Detective Sergeant Peter Malone told ABC.

The man is believed to be in his 40s and has been described as being of Mediterranean or Middle Eastern appearance with a medium build.

Police are urging anyone with information in relation to this incident to call Crime Stoppers on 1800 333 000.