The FBI told Dutch police that two brothers were being sought by Belgian authorities a week before the pair blew themselves up in suicide attacks in Brussels, the Dutch interior minister said on Tuesday.

Ard van der Steur was responding by letter to questions from Dutch legislators about Belgian brothers Ibrahim ("Brahim") and Khalid El Bakraoui, who prosecutors say took part in the March 22 attacks that killed 35 people, excluding the attackers.

A series of missteps and blunders by Belgium's security and intelligence agencies have come to light since the attacks, as well weaknesses in communication between intelligence agencies across Europe.