Calling for information, they issued a photograph of a man, dressed in a white shirt and jacket and wearing a dark hat as he pushed a luggage trolley through the airport.
The photograph was a crop of a larger frame, taken by a security camera and released earlier by Belgian media. The uncropped picture also depicts two other men, walking side by side with the wanted suspect. Prosecutors said the other men subsequently died in the suicide bombing at the airport.
In joint attacks on Tuesday, a second blast on a rush-hour train also killed a further 20 people.
The wanted notice on Tuesday follows a similar call issued by the investigating judge on Monday for a Najim Laachraoui, 25, who had traveled to Hungary in September with Paris attacks suspect Salah Abdeslam. He was arrested in Belgium last Friday.
The poor quality of the images on the two wanted notices left it unclear whether the man in the white shirt at the airport could be Lachraoui, whose picture was on the front pages of Belgian newspapers on Tuesday morning.