A suspect in the attack which took place at the Brussels international airport of Zaventem, is seen in this CCTV image made available by Belgian Police on April 7, 2016. [Photo/Agencies]

BRUSSELS - A man held on terrorism charges in Belgium has admitted to being the "man in a hat" seen on security camera footage at Brussels airport alongside two suicide bombers after attacks in the city killed 32 people, public prosecutors said on Saturday.

Prosecutors said that after being confronted with footage prepared by an investigational unit, Belgian Mohamed Abrini said he was the man police had been hunting since the bombings at the airport and on the metro on March 22.

"He had no other choice," a spokesman for Belgium's public prosecutors said. He had been held since Friday evening.

Abrini had been on Europe's most wanted list since December, after he was caught by a security camera at a motorway service station with suspected militant Salah Abdeslam while they drove to Paris two days before the attacks there that killed 130 people in November.

With the arrests and deaths in Brussels since a raid on March 15 put police on the trail of Abdeslam, all of the main known suspects in the Paris and Brussels attacks appear to have been taken off Europe's streets.

After leaving the airport, Abrini had thrown his light coat in a dust bin and later sold his hat, prosecutors added.

"He is charged with participation in the activities of a terrorist group and terrorist murder," the Belgian federal prosecutors office said in a statement.

Prosecutors charged four people, including Abrini, with terrorist activity for their suspected roles in the Brussels bombings and November's Paris attacks.

They were arrested on Friday, along with two others who were later released. Belgian police raided a suspected safe house in central Brussels on Saturday but found no weapons or explosives and made no further arrests.

Prosecutors said they also charged Osama K, who local media said was a Swede named Osama Krayem, adding they were able to identify him as the man present at the time of the attack on the Brussels metro station that same day.

Osama K was seen buying the bags used in the Brussels attacks in a shopping centre there, prosecutors said.

The other two were Bilal El Makhoukhi, who had already been convicted for working with jihadist recruiters, and a Rwandan named Herve B.M. on charges of helping Abrini and Osama K.