Under-fire Belgian authorities hunted a fugitive bomber Tuesday, a week after the attacks on the heart of Europe, as the city's airport warned it could take months to fully reopen despite holding a drill for a partial restart.
As Brussels struggled to get back on its feet, criticism of Belgium's handling of the case mounted after the sole suspect to be charged over the metro and airport attacks was freed for lack of evidence linking him to the carnage.
Prosecutors had charged the suspect, known as Faycal C., with "terrorist murder" and were investigating whether he was the third airport attacker who fled after his bomb did not detonate.
With his release on Monday, the hunt was back on for the so-called "man in the hat" seen in CCTV footage next to the two Islamic State group suicide bombers at Zaventem airport.
The airport, closed since the blasts wrecked the departure hall, was readying to stage a test run Tuesday involving hundreds of volunteer staff to determine if it was ready to resume flights, albeit in a very limited capacity, on Wednesday.
A temporary check-in facility has been set up and passengers will be subject to extra security checks.
Brussels Airport chief executive Arnaud Feist told L'Echo daily it could take "months" for the airport to be fully operational again.
A total of 35 people died in the attacks at the airport and Maalbeek metro station and 340 were injured, 96 of whom remain in hospital.
Many foreign nationals were among the victims, testament to the cosmopolitan nature of a city that is home to both the European Union and NATO.
Nearly all the fatalities have now been identified. The Indian government on Tuesday confirmed that a 31-year-old Indian man was on the metro train blown up by a suicide bomber.
While Belgian authorities were quick to identify all three bombers, the inquiry has been dogged by accusations that Belgium missed a series of leads in cracking down on a jihadist network linked to the Brussels attacks as well as the November 13 Paris massacres that killed 130 people.
Adding to the recriminations, Brussels mayor Yvan Mayeur said he regretted the release of the man identified by Belgian media as Faycal Cheffou, who claimed to be a freelance journalist.
Hinting at suspicions that the man was a militants recruiter, he told French media: "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."
The man's lawyer Olivier Martins told RTBF television that his client was let go because he had an alibi.
"He gave an alibi based on telephone analysis which showed that he was at home at the time of the attacks," Martins was quoted as saying.
Under pressure at home and abroad for an apparent series of missed clues in keeping tabs on criminals linked to militants networks, the Belgian government has admitted mistakes were made.
In the most glaring such example, Turkey accused Belgium last week of ignoring a clear and present danger after revealing it had deported airport suicide bomber Ibrahim El Bakraoui as a "terrorist fighter" last year after arresting him near the Syrian border.
Two Belgian ministers, including Justice Minister Koen Geens, offered to resign after the Turkish link emerged.
Underscoring the tense political climate in a notoriously complex and fragmented country, Geens on Tuesday called for unity.
"This is not the time to argue with each other. As far as I know the enemy is in Syria," he told VRT television.
In a bid to uncover the identity of the mystery third airport suspect, police have released video footage of a man in a hat and white jacket pushing a trolley with a large bag through the departure hall, next to suicide bombers Ibrahim El Bakraoui and Najim Laachraoui.
Bomb-maker Laachraoui's DNA was found on some of the explosives used in Paris.
Ibrahim El Bakraoui's brother Khalid, who blew himself up on a Brussels metro train shortly after the airport blasts, is meanwhile believed to have rented a property linked to Paris prime suspect Salah Abdeslam.
Abdeslam was arrested in Brussels on March 18 just metres from his family home after four months on the run.
Raids and arrests in Belgium, France and the Netherlands since the Brussels bombings have exposed a complex web of militants cells, underscoring the need for better European coordination in the fight against terrorism.