BRUSSELS—Belgian authorities on Friday arrested Mohamed Abrini, who they now suspect was the third attacker at the Brussels airport in March, U.S. and European officials said. He has been one of Europe’s most-wanted terror suspects since November for alleged links to the network behind the Paris massacre.
According to two officials, Belgian authorities suspect Mr. Abrini was the attacker who escaped from the national airport during the March 22 attacks, wearing a dark hat and a light-colored jacket. Thirty-two people were killed that day by suicide bombers at the airport and the Maelbeek subway station in central Brussels.
Authorities also arrested a man who is suspected of being involved in the attacks at the Maelbeek subway station on Friday, according to a U.S. official.
The arrests on Friday appear to be the first major breakthrough for Belgian authorities since the Brussels attacks.
If Belgian authorities can confirm that Mr. Abrini is the so-called “man in the hat” who has been the focus of an intense search since the attacks and confirm the involvement of the second alleged Maelbeek attacker, they will have resolved some of the key remaining questions about the attacks.
Belgian authorities were careful Friday with their public pronouncements after a previous misstep in identifying the third bomber. Belgian police arrested and charged Faycal Cheffou in the days after the attacks but later released him after establishing that he wasn’t at the airport on March 22. Federal prosecutors said they will give a press conference at 1930 GMT.
Mr. Abrini was previously believed to be a small-time member of the terror network. Growing up in Brussels, Mr. Abrini worked in a bakery, earning the nickname “Brioche,” before becoming involved first in petty crime and then with radical islamists in the Brussels district of Molenbeek.
Belgian federal prosecutors issued a wanted notice in late November for Mr. Abrini, a 31-year-old Belgian citizen, on suspicions he helped some of the Paris attackers, and warned he was armed and dangerous.
Mr. Abrini had been seen in surveillance video with Paris attacks suspect Salah Abdeslam at a gas station north of Paris two days before the attack there. At the time, Mr. Abrini was driving one of the cars that was used two days later to commit the Paris attacks.
Belgian officials and counterterrorism analysts emphasized that people involved in the attacks likely remain at large, describing a potentially extensive network.
The U.S. official said Belgian authorities also arrested Osama Krayem on Friday in connection with the attack on the subway. The official said that Mr. Krayem was seen on surveillance camera in the subway system before the attack talking with Khalid el-Bakraoui, the suicide bomber who struck at Maelbeek station.
The video footage also showed Mr. Krayem with a backpack similar to the one in which Mr. Bakraoui carried his bomb, the U.S. official said.
Mr. Krayem was identified by authorities as a lead suspect in the subway bombing in the days after the attack, officials said. Mr. Krayem, like several of the members of the network who are known to have planned and participated in the Paris and Brussels attacks, travelled into Europe along the migrant route, they said.
He used a fake Syrian passport with the name Naim Al Hamed, officials said.
Earlier Friday, Belgian federal prosecutors said in a statement they could confirm there had been several arrests connected to the Brussels attack. The arrests came after the Belgian prosecutors and police appealed on Thursday for help in the search for the third man.
They released additional video footage and said they had determined that he was seen with the two suicide bombers and then walked away from the airport after the explosions. Prosecutors said they were seeking the public’s help to find additional photographs and determine the path he took from the airport.
It is unclear whether the request for assistance yielded new clues or whether they were already closing in on the suspects.
Belgian authorities have come under fire, both internationally and at home, for their handling of investigations into local terror cells. Soon after the Brussels attacks, Turkey disclosed it had warned Belgium last summer that it suspected Ibrahim el-Bakraoui, one of the Brussels suicide bombers, had ties to Islamic State.
Belgian Prime Minister Charles Michel this week called criticism of the country’s counterterrorism efforts “completely wrong,” pointing to victories by Belgian authorities in foiling a terrorist plot targeting police in the east Belgian town of Verviers and arresting Mr. Abdeslam.
Mr. Abdeslam was captured on March 18 after a four-month manhunt. Soon after his arrest in Molenbeek, a Brussels district, Mr. Abdeslam said he had been planning follow-on attacks in Brussels.
Mr. Abrini co-owned a snack bar in the Brussels district of Molenbeek until December 2014. Both Mr. Abrini and Mr. Abdeslam were living nearby. Mr. Abrini’s snack bar was raided on Nov. 22, two days before Belgian officials issued the arrest warrant for him.
Molenbeek has been a focus of the terror investigations and home to several of the accused attackers including Mr. Abdeslam and Abdelhamid Abaaoud, the accused ringleader of the Paris attacks who was killed in a police raid days later.
Of athletic build, with dark hair, Mr. Abrini was believed to be “armed and dangerous,” according to a wanted notice issued by Europol, Europe’s police coordinating body.
Mr. Abrini’s younger brother flew to Istanbul in January 2014 and made his way to Syria, where he fought with an Islamic State unit, according to court documents and a person familiar with the investigation. The brother was killed in Syria in August 2014, according to the documents.
Mr. Abrini had traveled to the U.K. last summer, according to several people familiar with the matter.
Assistant Chief Constable Marcus Beale, the lead officer for the U.K.’s West Midlands Police Counter Terrorism unit, said security services were providing support to the French and Belgian investigations.
After Paris, people involved in the planning, officials said, were able to reconstitute and begin planning the strikes on Brussels.
The attacks in Brussels also followed quickly after the arrest of Mr. Abdeslam. Some analysts warned that a similar attempt can’t be ruled out following Mr. Abrini’s arrest.
“As long as you haven’t dismantled the whole network, there is a risk of follow-on attacks,” said Brice De Ruyver, a professor of criminology at University of Ghent and former Belgian government adviser. “But of course the more of those you arrest, the more information you get and the more links you can make that would help you complete the puzzle.”
—Matthias Verbergt in Stockholm and Alexis Flynn and Benoit Faucon in London contributed to this article.