BRUSSELS — The investigation into last week’s deadly attacks in Brussels extended farther across Europe on Sunday after Italian police arrested a new suspect thought to have helped Islamic State militants slip into Western Europe unnoticed.
Italian authorities said late Saturday that they had captured an Algerian man suspected of providing several Islamic State supporters with false identification documents, allowing them to evade authorities as they plotted attacks in Belgium and France.
“The Algerian arrested today in Salerno is part of a network of forgers of residency” documents, police said in a message on Twitter.
The arrest added to an emerging picture of the network behind the worst attack on Belgian soil since World War II and is another striking indication of the growing reach of the Islamic State beyond its strongholds in Iraq and Syria.
According to the Italian news agency ANSA, 40-year-old Djamal Eddine Ouali had been the subject of a Belgian arrest warrant since January. ANSA said he was suspected to have given the falsified papers to Salah Abdeslam, a suspected member of the cell that carried out the Nov. 13 Paris attacks, who is now in Belgian custody. Ouali is also believed to have furnished documents to Najim Laachraoui, suspected to have been one of the suicide bombers at the Brussels airport on Tuesday, and another man killed by Belgian authorities in a raid this month.
The attackers killed at least 28 people on Tuesday at Brussels Airport and, an hour later, in a crowded subway car.
In Belgium, another suspect linked to the attacks was charged, local media reported Sunday. The man, identified as Abderrahmane A., has been in custody since Friday and faces charges of belonging to a terrorist organization
Belgian police did not provide additional details on Sunday, as they expanded their hunt for new clues. Authorities conducted 13 searches in Brussels and other areas on Sunday, the federal prosecutor’s office said. Four people remain in custody.
The growing charge list may help ease tensions that were visible on Sunday even as Belgium, a largely Catholic country, marked Easter Sunday.
In a sign of the nervousness, riot police were deployed around a memorial site in the center of Brussels on Sunday afternoon after several hundred men dressed in black poured into the area. The men, apparently soccer fans, disrupted a mostly quiet vigil and began shouting slogans against the Islamic State and, according to some media reports, immigrants. The crowd later dispersed.
Authorities had hoped to avoid this kind of alarm when they urged organizers to postpone a solidarity rally planned for Sunday, acknowledging that police could not provide adequate security.
Across the continent, fears of renewed attacks remain elevated. In St. Peter’s Square at the Vatican, worshipers were subject to tight security as they flocked to hear Pope Francis deliver his Easter address. Speaking to the crowed, the pope labeled terrorism a “blind and brutal form of violence,” according to the Associated Press.
In Iraq and Syria, the Islamic State remains defiant even as it faces pressure from the United States and its allies from the air and from forces loyal to Syrian President Bashar al-Assad on the ground. On Saturday, Syria claimed to have recaptured the historic city of Palmyra, under Islamic State control for months.
Over the weekend, militants continued to celebrate attacks that they said had demonstrated the weakness of Western defenses. In a video released Saturday, a Dutch-speaking fighter, identified as Abu Hanifa al-Beljiki, addressed the government of Belgium.
“You learned nothing from the lessons of Paris, because you continued fighting Islam and the Muslims,” he said, according to a transcript from the SITE Intelligence Group. “For this I want to tell you that the attack in Brussels is reaping what you had sown with your own hands.”
The video followed Belgian authorities’ announcement Saturday that they may have found the most-wanted remaining suspect in Tuesday’s attacks. It was a welcome development for the government in Brussels, facing widespread criticism over its failure to chase down leads that might have helped prevent the attacks.
According to a European security official, the man is Fayçal Cheffou, whose explosives-laden suitcase apparently did not detonate.
The man, whom Belgian officials have not fully identified, was charged Saturday with “participation in the activities of a terrorist group, terrorist murders and attempted terrorist murders.”
According to Belgian media, Cheffou has identified himself as a journalist in the past and has promoted radical Islamist beliefs.
Belgian authorities also have charged a man identified as “Rabah N.” with taking part in a terrorist group and another man, identified as “Aboubakar A.,” with a terrorism-related offense.
Belgian media has reported that Abderrahmane Ameroud, presumably the same person as the one charged on Sunday, is another person linked to the attacks. France sentenced the Algerian to seven years for recruiting fighters for Afghanistan. The case was tied to the 2001 assassination of Ahmed Shah Massoud, the legendary Afghan guerrilla leader.
It is not known what exactly each person is suspected to have done.
The new charges come as Belgian authorities admit missteps in their handling of terrorism investigations.
Investigators acknowledged late last week that they did not question Abdeslam extensively after his March 18 arrest, possibly missing clues that might have helped them avert the disaster four days later.
On Sunday, Interior Minister Jan Jambon defended to local media the government’s decision-making during last week’s attacks. He has come under fire for failing to protect Brussels after the initial attack at the airport.
More than 300 people were wounded in the attacks, Belgian officials have said. Nearly half of the victims were foreign nationals, including at least two Americans. According to Belgium’s Foreign Ministry, not all of those wounded have been identified because some of them remain in a coma.
Annabell Van den Berghe contributed to this report.