Detectives investigating two armed robberies and an attempted armed robbery at three Sydney banks have released CCTV footage of a man they believe might be able to assist with their inquiries.

In the first incident on Wednesday 4 May 2011, a staff member was threatened with a firearm just before 1.30pm at a bank on Mona Vale Road, St Ives. The offender demanded cash before fleeing the scene.

There were a number of employees and customers in the bank at the time, including a young child.

In the second incident, just after midday on Friday 24 June 2011 at a bank on the Pacific Highway, St Leonards, a staff member was threatened with a firearm before security screens were activated. The offender fled empty-handed.

In the third incident, just before 11.45am on Thursday 30 June 2011, staff at a bank on New South Head Road at Edgecliff were threatened with a handgun before an offender stole a sum of cash and fled the scene.

 No shots were fired during any of the incidents and no-one was injured.

 Police responded quickly to each incident with the crime scenes forensically examined by specialist officers.

 Detectives from State Crime Command’s Robbery and Serious Crime Squad have been investigating the robberies under Strike Force Reedy.

 They have released CCTV footage of a man they believe might be able to assist with their inquiries.

 He is described as being aged in his 30s to 40s, of Caucasian appearance, 185cm tall with a medium build and fair complexion. He was seen riding a silver-coloured mountain-bike.