Belgian prosecutors have charged “The Man in the Hat” _ the most wanted suspect in the Brussels attacks.

The man, wearing a hat and a light-coloured jacket, was seen in a CCTV picture with two others who were about to blow themselves up at Brussels airport on Tuesday.

The carnage at Brussels Airport. Facebook.

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According to Belgian state broadcaster RTBF, the man is Belgian freelance journalist Faycal Cheffou, who was charged on Saturday with taking part in the activities of a terrorist group, and actual and attempted terrorist murder.

Also charged yesterday were Aboubakar A. and Rabah N., who are accused of terrorist activities and membership of a terrorist group.

Rabah N. was wanted in connection with a related raid in France this week that authorities say foiled an apparent attack plot.

The authorities also said that a man arrested on Friday after being shot in the leg at a tram stop in the Brussels district of Schaerbeek was being held for a further 24 hours.

He was identified as Abderamane A. and was one of three people arrested on Friday.

That operation was linked to the arrest in Paris on Thursday of an Islamist convicted in Belgium last year and suspected of plotting a new attack, Belgian prosecutors said.

The Doel nuclear plant in Belgium. Getty

With Brussels still on high alert, organisers called off a “march against fear” planned for Sunday after officials urged people to stay away to spare over-taxed police.

“The security of our citizens is an absolute priority,” said march organiser Emmanuel Foulon.

“We totally agree with the authorities’ request to delay this plan for a later date.”

Highlighting the jittery national mood, the murder this week of a security guard employed at a site in Belgium holding radioactive materials has stoked debate about the risks of militants attempting some kind of nuclear attack.

On Saturday prosecutors denied media reports the guard had had his access badge stolen and the implication it could have been a motive for his murder.

On Thursday, French language newspaper DH (Derniere Heure) had reported the suicide bombers who blew themselves up on Tuesday originally considered targeting a nuclear site, but the arrests of suspect militants forced them to speed up their plans and instead switch focus to Brussels.

Late last year, investigators found a video tracking the movements of a man linked to Belgium’s nuclear industry during a search of a flat as part of investigations into the Islamist militant attacks on Paris on Nov. 13.

The suicide bomb attacks targeting Brussels airport and a rush-hour metro train on Tuesday killed 31 people, including three of the attackers, and injured hundreds more. Islamic State has claimed responsibility.

Officials said 24 victims from nine different nationalities had been identified so far from the attacks. Four victims remain unidentified.

With AAP