Belgium's Federal Prosecution Office says that the terror group that struck Brussels on March 22 initially planned to launch a second attack on France.

But the office said Sunday that the perpetrators were "surprised by the speed of the progress in the ongoing investigation" and decided to rush an attack on Brussels instead.

Two suicide bombers killed 16 people at Brussels Airport on March 22. A subsequent explosion at Brussels' Maelbeek subway station killed another 16 people the same morning.

Investigators have found intimate links between the cell behind the Brussels attacks and the group that killed 130 people in Paris on Nov. 13.