BRUSSELS — A file with the floor plan and photographs of the office of the Belgian prime minister was found on a laptop computer discarded in a garbage can last week by one of the terrorists linked to the Brussels attacks, a government official said Wednesday.
The computer was found during a raid on Rue Max Roos in the Schaerbeek neighborhood of Brussels several hours after the attacks on March 22.
Several Belgian newspapers, including L’Écho, De Tijd and De Morgen, reported that the information about the prime minister’s office, on Rue de la Loi, the site of regular meetings by Cabinet ministers, had been found on the laptop.
A Belgian official familiar with the investigation confirmed those reports Wednesday, but spoke on the condition of anonymity because he was not authorized to speak publicly about the case.
On the same computer, investigators found a statement — described by the authorities as a will — by Ibrahim el-Bakraoui, one of three suicide bombers who carried out the attacks. In that statement, el-Bakraoui described himself as increasingly desperate and fearful of ending up in prison.
El-Bakraoui and another man, Najim Laachraoui, blew themselves up at Brussels Airport, and el-Bakraoui’s younger brother, Khalid, detonated a suicide bomb at the Maelbeek station.
The authorities are seeking a third airport attacker, a man seen on surveillance footage wearing a white jacket. They are also, according to Belgian news reports, looking for another person involved in the subway blast.
The toll from the attacks at Brussels Airport and the Maelbeek subway station was revised downward Tuesday, to 32 from 35, as the authorities finished identifying the victims.
Local news reports said the discarded computer also contained precise information about the prime minister’s residence, which is known as the Lambermont and is steps from the U.S. Embassy. Secretary of State John Kerry met Prime Minister Charles Michel at the residence Friday.
L’Écho reported that Michel had been informed about the findings, that security around the office had been reinforced, and that the United States had been asked to help analyze and decrypt information on the computer.
On Wednesday, the Dutch minister of security and justice, Ard van der Steur, said that the intelligence division of the New York Police Department had warned the Dutch government, via the embassy in Washington, on March 16 that the el-Bakraoui brothers had links to terrorism.
Van der Steur had said that the warning had come from the FBI, but in a statement Wednesday, he acknowledged that he had erred in testimony before the Dutch Parliament.
It was not clear how the police in New York had become aware of the el-Bakraoui brothers, or why they had relayed the information to the Dutch authorities.
News outlets in the Netherlands have reported that the government there passed the warning on to the Belgians on March 17, one day after receiving it.
The Turkish government arrested Ibrahim el-Bakraoui near the Turkish border with Syria in June. Officials there alerted the Belgian government, and then deported him to the Netherlands at his request.
The el-Bakraoui brothers had extensive criminal records. Ibrahim el-Bakraoui received parole in October 2014 from a nine-year prison sentence for attempted murder; Khalid el-Bakraoui had a history of carjackings.
Whether the Dutch and Belgian authorities sufficiently appreciated the gravity of the threat posed by the el-Bakraoui brothers is one of many strands that lawmakers and intelligence agencies are reviewing in the aftermath of the attacks, the worst violence on Belgian soil in decades.
One of the most significant strands involves Reda Kriket, who was arrested last week in France and accused of plotting a new terrorist attack.
Kriket, according to court records, raised money for a network of militants in 2012 and 2013 and traveled to Syria in late 2014. Kriket was well known to the security services in both France and Belgium, and last year he was named in a court proceeding with Abdelhamid Abaaoud, the on-the-ground chief planner of the attacks that killed 130 people in and around Paris on Nov. 13.
On Wednesday, an investigative judge in Paris who focuses on counterterrorism is expected to place Kriket under formal investigation, and hand up preliminary charges. At midday, Kriket was transferred from the headquarters of France’s domestic intelligence agency, in a northwestern suburb of Paris, to the Palais de Justice, the main courthouse in the heart of the capital.