Najim Laachraoui, the main surviving suspect in the twin bomb attacks in Brussels that killed at least 34 people is still at large.
Laachraoui has been identified as one the three men captured in CCTV footage at Brussels airport before the attacks on Tuesday. He slipped through the fingers of security operatives leaving the largest quantity of explosives at the airport in a backpack, but they never detonated.
Belgian media said Laachraoui, a 24-year-old Belgian national who was born in Morocco, knew suspected Paris terror attacks planner Salah Abdeslam. Abdeslam was arrested in Brussels on Friday.
Two suspected suicide bombers who blew themselves up in the attacks at the airport and the central Maelbeek metro station were named as brothers Khalid and Ibrahim el-Bakraou.
One of the el-Bakraoui brothers is also believed to have provided ammunition and weapons for the Paris attacks in which gunmen opened fire on bars and at a rock concert at the Bataclan, according to reports.
Laachraoui was reported to have traveled to Syria in 2013 to help recruit fighters for the Islamic State, according to authorities.