The still photograph shows young three men with dark hair, pushing laden luggage trolleys. Their identities were unknown.
Belgian federal prosecutors had asked media in a statement earlier on Tuesday not to release the picture for the good of the investigation, but it leaked on social media, the VTM broadcaster said.
Police issued a wanted notice for a man suspected of involvement in Tuesday’s bomb attacks at Brussels airport that left at least 10 people dead.
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.
In joint attacks on Tuesday, a second blast on a rush-hour train also killed a further 20 people.
Broadcasters RTL and RTBF reported anti-terrorist police were carrying out searches in the Brussels district of Schaerbeek and Jette.
Belgian media earlier carried pictures from airport security cameras showing two people in black and a third person wearing a hat and following just behind.