Belgian prosecutors on Thursday launched a fresh appeal for help to find the suspected surviving attacker in last month’s Brussels airport bombings, the so-called "man in the hat," releasing a video of his escape route.

Belgian prosecutors on Thursday launched a fresh appeal for help to find the suspected surviving attacker in last month's Brussels airport bombings, the so-called "man in the hat," releasing a video of his escape route.

Police have been desperately searching for the man seen on CCTV next to the two suicide bombers who blew themselves up at the airport on March 22 in coordinated attacks that also struck a Brussels metro station. A total of 32 people died.

The newly released police video shows the suspect, wearing a hat and a light-colored jacket, fleeing the airport's departure hall after the bombs went off at 07:58 am on March 22.

CCTV footage shows him continuing his route on foot towards central Brussels where surveillance cameras lose track of him at 09:50 am.

Along the way, the man discards his jacket and at one point appears to be on the phone.

"We especially appeal to anyone who might have filmed or think they have photographed the suspect," spokesman Eric Van der Sypt told a press conference to present the video.

Investigators are urgently looking for the jacket, described in a statement as "bright with a hood which is dark inside".

"Especially the jacket interests us," the prosecutor office's spokesman told reporters.

Potential witnesses are asked to contact the police using a specially provided phone number and email address.

Last week police asked all residents and business owners in the Brussels region who have external surveillance cameras not to delete any footage from March 15 onwards.

Belgian authorities have come under fire for their handling of the case, especially after close links emerged between the Brussels attackers and those behind the Paris terror assaults last November which left 130 dead.

Both attacks were claimed by the ISIL group.