Belgium charges four with participating in terrorism

Arrested suspects Mohamed Abrini, Osama K., Herve B. M. and Bilal E. M. have all been charged with participating in "terrorist murders" and the "activities of a terrorist group" in relation to the March 22 suicide bombings at Brussels' airport and subway, which killed 32 people and wounded 270 others.

Two other suspects arrested in the last couple of days were released "after thorough interrogation."

A prosecution office statement said it was "not possible yet to confirm" if Abrini was the third suspect – dubbed "the man in the hat" – who escaped Brussels Airport while two suicide bombers he was seen on video with blew themselves up.

Authorities have issued urgent pleas to the public for any information on the man in the hat.

The charges follow days of arrests and raids in in Brussels and could give investigators new insights into the Islamic State group cell believed to have carried out both the attacks in Brussels and the November 13 attacks in Paris, which left 130 dead in the French capital.

Osama K. was identified by Swedish media as Osama Krayem, who is known to have left the Swedish city of Malmo to fight in Syria.

The prosecutor's office accuses him of being the second person present at the attack on the Maelbeek subway station in Brussels and of being present at a shopping mall where the luggage used in the airport attack was purchased.

Swedish officials had no immediate comment on Osama K.

The statement describes Herve B. M. as a Rwandan citizen arrested at the same time as Krayem who is accused of offering assistance to both Abrini and Krayem.

The attacks in France and Belgium were the two biggest carried out by the Islamic State group in Europe over the past year.

The arrests may help investigators unravel the links between the attacks and IS, the radical Muslim group that controls territory in both Iraq and Syria.

Krayem had earlier been identified posting photos from Syria on social media, according to Magnus Ranstorp, a counterterrorism expert at the Swedish National Defence College.

"He also tried to recruit people in Malmo," Ranstorp told The Associated Press.

The detentions were a rare success for Belgian authorities, who have been pilloried for mishandling leads in the bombings investigation.

But despite multiple arrests, Brussels remains under the second-highest terror alert, meaning an attack is still considered likely.

"There are perhaps other cells that are still active on our territory," Belgian Interior Minister Jan Jambon told RTL television on Saturday.