MADRID — In a major anti-terrorism sweep carried out as European leaders arrived in Brussels for a summit, Belgian police on Thursday arrested 14 suspects allegedly linked to Al Qaeda, including one who police believe was close to launching a suicide attack.
The arrests were made by 242 officers who conducted 16 searches in Brussels and Liege, while French police arrested two additional suspects tied to the group, anti-terrorism officials said.
The raids came after a yearlong investigation in which police tracked militants, mainly Belgians and French of North African origin, who traveled to Al Qaeda hide-outs in Pakistan and Afghanistan, fought against Western troops and then returned to Europe, investigators said.
Authorities said they grew alarmed during the last week when surveillance showed that a key suspect had returned from South Asia on Dec. 4 and begun making what police believe were preparations for a suicide attack. Investigators feared the attack might target the 27 leaders of the European Union, who began the two-day summit in Brussels on Thursday.
"We don't know where this suicide attack was envisioned," chief federal prosecutor Johan Delmulle said at a news conference. "It could concern an operation in Pakistan [or] Afghanistan, but it could not be totally ruled out that Belgium or Europe were a target."
The investigation featured one of the largest recent deployments of anti-terrorism investigators and wiretaps in Belgium. The allegations resemble a pattern detected in Britain and other European countries: Militants travel to the Afghan-Pakistani border zone and return to target their homelands, often directed from afar by Al Qaeda masterminds.
Belgian investigators said they had intercepted Internet communications from militants who described their experiences in combat in Afghanistan during the last year.
"They would say things like, 'I wasn't able to communicate for a while because it was really tough, we got bombed by the Americans,' " said a Belgian anti-terrorism official who requested anonymity because of the continuing investigation. "Or they talked about helping a brother who had been wounded in combat."
The combatants in Afghanistan were Belgians of North African descent, authorities said. The suspects were active in the underworld of Belgian robbery gangs before they became Islamic extremists, the anti-terrorism official said.
The investigation gathered steam as three suspects returned in recent months, and particularly when the suspect who arrived eight days ago sent "disturbing messages," authorities said.
The suspect discussed saying goodbye to loved ones and talked about a video that had been prepared for them, authorities said. Investigators believe the video might be a "martyrdom" message because the suspect's actions resembled the classic preparations of militants before suicide attacks.
"The information revealed that the suspect had gotten the green light to execute an operation from which he would not return," Delmulle said. "This information had to be seen in connection to a message intercepted Dec. 7 which talks about evacuating women and children. The exact meaning of the message is not yet clear, but it is known that before previous attacks that wives and children of people involved were sometimes relocated in safe places."
Despite fears of an imminent attack, no explosives were found, authorities said.
Authorities said one alleged leader arrested in Brussels was Malika Aroud, the Belgian widow of an Al Qaeda suicide bomber who killed anti-Taliban warlord Ahmed Shah Massoud in Afghanistan two days before the terrorist attacks of Sept. 11, 2001. Aroud has survived several attempts to prosecute her. She is revered in militant circles because of her fierce eloquence and because she came to know Al Qaeda leaders while living in Afghanistan in 2001, investigators say.
"She is really very important and very clever," said a Belgian law enforcement official, who requested anonymity because the investigation remains open.
Police say Aroud's second husband, Moez Garsaouli, also served as a leader of the group and remains a fugitive overseas. He allegedly oversaw the travel of Belgian and French recruits through Turkey and Iran to the tribal areas in northwestern Pakistan near the Afghan border, authorities said.
"The investigation shows that direct contacts exist between the group around the suspect M.G. located in Pakistan and in Afghanistan and important people in the Al Qaeda organization," Delmulle said.
Two Belgian anti-terrorism officials confirmed that "M.G." referred to Garsaouli.
Last year, the couple were among a dozen suspects arrested in a pre-Christmas operation. At the time, prosecutors alleged that they had detected plots to free an Al Qaeda convict from a Belgian prison and to carry out a bombing in Brussels.
Although authorities issued a terrorism alert, the suspects were all released without charges -- a frequent occurrence in a nation that has weaker anti-terrorism laws than its European neighbors.
Nonetheless, Belgium's justice and interior ministers said Thursday that the investigation confirmed intelligence that a bona fide threat existed last December.
"The operation carried out today proves that at the time, the evaluation of the threat by our services was correct," Justice Minister Jo Vandeurzen and Interior Minister Patrick Dewael said in a statement. "Very probably, an attack in Brussels was foiled."
The suspects arrested Thursday will be questioned, and judges will decide in the coming days if there is enough evidence to charge them.
Staff writer Achrene Sicakyuz in Paris contributed to this report.