A man widely reported to be the third individual seen in surveillance video with two suspected suicide bombers at the Brussels airport was released on Monday for lack of evidence.

Belgium's federal prosecutor's office said it had freed a man it had named only as Faycal C., adding it had no evidence to justify holding him. He had been charged on Saturday with "terrorist murder."

"The evidence which led to the arrest of the man named as Faycal C. has not been backed up by the ongoing investigation. As a result, the person has been freed by the investigating magistrate," the prosecutor's office said.

The announcement was a major blow to an investigation that had netted half a dozen people charged with lesser offences in Belgium and others in the Netherlands, Italy and France, where officials said the same network had planned another attack.

Belgian media had identified the man as Faycal Cheffou, a self-styled freelance journalist, and a source close to the investigation had said officials believed he was the so-called "man in the hat" in the footage.

'Faycal C.' released for lack of evidence1:37

Today, Belgian police issued a new appeal for information about the man in the hat. 

The man is seen pushing a trolley with a suitcase through the airport. An official notice from police said they were seeking to formally identify the man, who is suspected of dumping his case, which contained a bomb, before running from the terminal. 

A Europe-wide hunt for suspects has revealed links with the network that killed 130 people in Paris last November, as well as foiling a new potential attack on France last week, officials said. But several suspects are reported to be still at large.

3 more arrested 

Belgian federal prosecutors on Monday said three more people have been ordered held on charges of participating in terrorist activities.

Prosecutors did not immediately release details on the alleged terrorist acts or whether they were linked to last week's suicide bombings at Brussels airport and in the Brussels subway that killed at least 35 people and injured some 270 others, 96 of which remain in hospital.

The three charged by an investigating magistrate — identified as Yassine A., Mohamed B. and Aboubaker O. by the federal prosecutors office — were among four people detained during 13 police raids Sunday in Brussels and the northern cities of Mechelen and Duffel.

A fourth person detained was released without charge, the prosecutors' statement said.

Belgium Attacks

Belgian soldiers stand guard next to one of the memorials to the victims of the recent Brussels attacks, at the Place de la Bourse in Brussels, on Sunday. (Alastair Grant/Associated Press)

On March 22, two suicide bombers blew themselves up at Brussels Airport and a third did the same in a Brussels subway train.

The attacks caused great damage to the airport's departure area. On Tuesday, one week after the bombings, Brussels Airport will test its capacity to partially resume passenger service, an airport official said Monday. But she said it's too early to say when passenger service might actually resume.

Florence Muls, the airport's external communications manager, said 800 staff members on Tuesday will test temporary infrastructure and new arrangements designed for passenger check-in. Firefighters and the Belgian government must approve the new system, Muls said, before Brussels Airport can resume handling passenger traffic.

Before the bombings, Brussels Airport served some 600 flights a day and 23.5 million passengers per year. 

More 'must be done,' Washington says

The White House says Europe must still do more to improve security measures to prevent incidents like the March 22 attacks in Brussels.

White House press secretary Josh Earnest said U.S. President Barack Obama made that point after the November attacks in Paris. He said the president had pushed for European security agencies to improve information sharing among themselves and also with the U.S.

Earnest said there's been some progress made. But he said there is more that "can and must be done."

The White House isn't commenting specifically on a judge's order to release Faycal C. The U.S. says it's continuing to offer assistance to Belgian authorities.

With files from The Associated Press