Belgian prosecutors have released new footage of the key surviving Brussels airport attacks suspect, showing the route he took after leaving the area.
They have asked members of the public who saw the man to come forward.
The man was tracked on CCTV footage until 09:50 local time and was wearing a hat and a light-coloured jacket, officials said.
They said he discarded the jacket, and have asked the public to report if it has been found.
The 22 March attacks by so-called Islamic State (IS) on Brussels airport and a metro station killed 32 people.
Three attackers are believed to have targeted the airport, with two dying in the bomb blasts.
The “man with the hat”, as prosecutors called him, was captured pushing a trolley at Brussels airport next to the two suicide bombers in previously released CCTV footage.
Federal prosecutor Eric Van Der Sypt asked for those who “might have filmed or taken a photograph of the suspect” or believe they have any useful information, to call 0800 30 300 (in Belgium) or 003225544488 (from abroad).
Separately Salah Abdeslam, the main suspect in the Paris terror attacks of 13 November, will not be extradited from Belgium to France for several more weeks, his lawyer Sven Mary has said.
Belgian authorities want more time to question Abdeslam in connection with a 15 March shootout in Brussels during a police raid, he said.
According to prosecutors, Abdeslam's fingerprints were found in the apartment where Algerian terror suspect Mohamed Belkaid was shot dead after opening fire on police.
Abdeslam was arrested three days later in Brussels' Molenbeek neighbourhood.
He is believed to be the only surviving member of the group that killed 130 people in Paris last November in a series of co-ordinated attacks also claimed by so-called IS.