The Netherlands said on Tuesday the FBI warned it about the Brussels suicide bombers six days before the attacks. The Dutch said they passed the information on to their Belgian counterparts.

Dutch Justice Minister Ard van der Steur said the FBI's report contained "notification of Ibrahim El Bakraoui and his brother Khalid's criminal backgrounds and Khalid's terrorist background."

The following day "the issue came up during bilateral contact between the Dutch and Belgian police," said Van der Steur.

"The radical background of both the brothers was discussed," he told parliament.

Airport to stay shut

Brussels airport will remain closed on Wednesday, eight days after suicide bombers killed dozens of travelers and badly damaged the airport's departure hall.

When the airport will reopen for partial service is unclear, though it is expected to be months before it is fully operational.

Belgian's health minister, meanwhile, lowered the death toll from 35 to 32, citing an overlap due to some victims having dual nationality.

The figure does not include the three suicide bombers, two of whom struck at the airport, while the third blew himself up a short time later at a busy metro station.

The victims, who have now all been identified, included 17 Belgians and 15 foreigners - among them German, British, Chinese, Dutch, French, Italian, Swedish and US nationals.

Hundreds of airport employees participated in a large-scale test run Tuesday to determine if partial service could be resumed on Wednesday.

No explanation was given, but it was determined that the airport was not ready to reopen.

The authorities are now reviewing the results of the test run, according to airport spokeswoman Anke Fransen.

"We hope to reach a decision on a partial reopening of the airport in the course of (Wednesday) morning," she said.

Brussels Airport chief executive Arnaud Feist had earlier warned that it could be "months" before the airport was fully operational again.

'Very thin line'

Controversy continues to surround the March 22 attack and the ongoing investigation. On Monday, police released Faycal Cheffou, who had been suspected of being the third would-be suicide bomber at the airport, whose vest didn't explode.

Prosecutors charged him with "terrorist murder," but subsequently concluded he was not the suspect.

On Tuesday, however, Brussels mayor Yvan Mayeur cast doubt on the decision to release Cheffou.

"There is a very thin line between an agitated radical and a radical recruiter, and in this case the judge probably didn't want to cross that line," Mayeur said.

Cheffou's lawyer Olivier Martins said his client was released for good reason.

"He gave an alibi based on telephone analysis which showed that he was at home at the time of the attacks," Martins said.