Khalid El Bakraoui was involved in planning the attacks in Paris on the evening of Nov. 13 2015 in which 130 people were killed. He then blew himself up in the Brussels metro last March, as part of coordinated attacks that killed 32 people.
Belgian police detained a man and a woman in a house search on Wednesday, prosecutors said.
The woman, identified as Meryem E. B., was released under strict conditions. The man, named as Farid K., remained in custody. He is also charged with participating in the activities of a terrorist organization.
"They are suspected of having provided Khalid El Bakraoui with the false documents later used in preparation for the Paris attacks," prosecutors said in a statement.
Bakraoui rented, under a false name, an apartment in the city's Forest borough where police hunting Paris suspect Salah Abdeslam killed another suspected militant in a raid weeks before the attacks in Brussels.
He is also believed to have rented a safe house in the southern Belgian city of Charleroi used in preparation for the Paris attacks.--Reuters