Federal prosecutors said in a statement that fugitive Salah Abdeslam, who was in Paris at the time of the attacks and whose brother blew himself up, traveled twice to Budapest in September using a rental car.
On Sept. 9 he was subject to a control at the Austrian-Hungarian border in a Mercedes in the company of two other men, using fake Belgian identity cards with the names Samir Bouzid and Soufiane Kayal.
The cards and photographs of the suspects, seemingly taken from closed circuit television footage, can be found on www.police.be.
Federal prosecutors said the same false identity of Soufiane Kayal was used to rent a house in the Belgian town of Auvelais that was searched on Nov. 26.
The other false identity card, for Samir Bouzid, was used four days after the attacks to transfer 750 euros ($817) at a Western Union office in Brussels to Hasna Aitboulahcen, who died in a police assault in St Denis on Nov. 18.