RTBF named the two as Khalid and Ibrahim El Bakraoui, saying Khalid last week rented an apartment in Brussels under a false name where police found Abdeslam's fingerprints after a raid.
Belgian authorities are also “actively searching” for the third member of a team of bombers who targeted Brussels’ Zaventem Airport.
Police arrested Abdeslam, Europe's most wanted man, in a dramatic operation in Brussels on Friday.
Meanwhile, Belgians flocked in their hundreds to the Place de la Bourse in the ancient heart of the city to grieve as the country held three days of national mourning.
The Belgian capital, home to the European Union headquarters, was left reeling Tuesday after some 35 people were killed in bombings at Zaventem Airport and on a metro train.
A lone musician played a cello as a mourner waved a banner reading "United against hate" and another message scrawled on the ground said: "Christians + Muslims + Jews = humanity".
Belgian Prime Minister Charles Michel joined the mourners after dark fell and European Commission president Jean-Claude Juncker also paid homage to the dead.