Belgian law enforcement officials questioned terror suspect Salah Abdeslam for about one hour between the time of his arrest Friday and the Brussels attacks Tuesday, according to Abdeslam's attorney and two sources familiar with the investigation.

The session Saturday at a prison in Bruges yielded no information about the imminent threat because the prosecutors started chronologically and focused first on Abdeslam's involvement in last November's Paris terror attacks, the sources said.

Despite the discovery of detonators, weapons, and Abdeslam's fingerprints in a safe house days earlier and growing evidence that the Brussels terror network was stronger than previously understood, law enforcement officials only briefly questioned Abdeslam because he was still recovering from surgery after being shot in the leg during his apprehension, according to a senior Belgian security official, who asked for anonymity to speak about the investigation.

“He seemed very tired and he had been operated on the day before,” the official said, adding that law enforcement officials did not question him again before Tuesday.

"They were not thinking about the possibilities of what happened on Tuesday morning," said a second source with knowledge of the process.

Attorney Sven Mary, who represents Abdeslam, confirmed to POLITICO that prosecutors had spoken only briefly with his client between his arrest and the time of the attacks.

"Once. Yes," Mary said Thursday outside the court where he attended a pre-trial hearing related to the Abdeslam case.

The Belgian prosecutor confirmed in a statement Friday that officials had questioned Abdeslam for one hour on the Paris attacks. A second hearing took place later Saturday but “it was linked to a European arrest warrant issued by French legal authorities.” During the second hearing, Abdeslam asserted his right to remain silent, and didn’t make any further statements, the prosecutor's office said.

Abdeslam was questioned again “immediately” after the Brussels attacks, but he refused to speak, the statement said.

The capture of Abdeslam, who had eluded authorities for four months, began as a proud moment for Belgian and French authorities. In retrospect, it looks like a missed opportunity. Law enforcement officials did not interrogate Europe's most wanted terror suspect at any length about possible future attacks. Belgium's threat analysis center didn't raise the public alert level after his arrest.

Even as officials warned publicly over the weekend that further attacks were possible, Belgian authorities decided not to raise the terror alert to its highest level.

The decision of investigators to not focus on drawing out information from Abdeslam about imminent threats, as well as the admission after the airport and subway attacks that the suspected bombers had been known to law enforcement authorities, is sure to feed growing criticism of the Belgian government's competence on counterterrorism.

The country's law enforcement lapses, exacerbated by a fragmented political system, have allowed a strong network of jihadi cells to turn Belgium into one of their most significant bases of operation in Europe. Belgium has 451 citizens who went to fight in Syria and Iraq (in per capita terms, the most of any country in the EU), and 117 of them have returned home, according to the latest estimates provided by the justice ministry.

Even as officials warned publicly over the weekend that further attacks were possible, Belgian authorities decided not to raise the terror alert to its highest level — as they did several days after the Paris attacks — because they said they had no evidence that another strike was imminent.

“We can only warn our citizens on the basis of concrete information and plans," said Peter Mertens, spokesman for the interior ministry's crisis center. "In this case, we didn’t have enough to raise it to 4. Our services didn’t know about this attack. We didn’t have precise information on the preparation of an attack."

Abdeslam's arrest appears to have quickened the terror plot. Belgian prosecutors on Wednesday disclosed the discovery of a written statement from Ibrahim el Bakraoui, one of the alleged airport bombers, that mentioned he was running out of time, feared for his safety and didn't want to end up in a jail cell. The note included such lines as “We have to get a move on,” according to the Belgian security official.

“We must clearly address the shortcomings of the Belgian security services,” Günther Oettinger, the European digital commissioner, told German newspaper Bild. “In Brussels alone there are several different police agencies, which do not cooperate sufficiently. This cannot continue.”

Lost time

Belgian and French law enforcement authorities spent much of last weekend talking about what went right in their arrest of Abdeslam.

Belgian Prime Minister Charles Michel and French President François Hollande held a celebratory press conference on Friday evening and praised their countries' cooperation. Privately, Belgian officials crowed that, unlike French law enforcement officials, who had killed Paris terror suspect Abdelhamid Abaaoud following a manhunt in November, they had gotten their target alive.

During his short interrogation session Saturday, Abdeslam told investigators that he intended to blow up the Stade de France during the Paris attacks, but "changed his mind," according to the Belgian security source. Law enforcement officials discounted the theory, believing instead that the detonators had malfunctioned in Paris and that the discovery of the new detonators proved he was planning another attack.

They hoped to investigate further, according to the source. But Belgian law enforcement officials said they think the public disclosure Saturday by French prosecutor François Molins about the interrogation prompted the attackers to speed up their plan.

“We would have had more time to prevent [the attacks in Brussels] had the French not leaked this to the press,” the source said.

A Belgian official told POLITICO that Abdeslam was supposed to have taken part in the bomb attacks that hit the Belgian capital.

'Two sorts of errors'

The signs of imminent attacks appear abundant in hindsight.

Intelligence officials knew before the attacks that Abdeslam, Abbaoud and the el-Bakraoui brothers, who helped carry out Tuesday's attacks, knew each other and had “family and friendship ties,” according to a senior counter-terrorism official.

“It is a clan which has chosen as its headquarters the neighborhood of Molenbeek and Schaerbeek,” the counter-terrorism official said. “What these men did is reproduce a structure they had at home here, they brought a tiny slice of Morocco to Brussels.”

In November, police released a wanted notice stating they had found DNA traces of Najim Laachraoui, an experienced bomb maker connected to the Paris attacks and one of the alleged Brussels airport suicide bombers, in a rented house in Auvelais and an apartment in Schaerbeek.

There is also mounting evidence that Belgium had not adequately tracked known terrorists.

On Wednesday, Turkish President Recep Tayyip Erdoğan said one of the men who carried out Tuesday’s attacks — reportedly Brahim el-Bakraoui — had been arrested in Turkey last year and deported, but Belgium ignored warnings that he was a “foreign terrorist fighter.”

On Thursday, Belgian prosecutors acknowledged that Khalid el-Bakraoui, one of the suicide bombers who killed 20 people in the subway, had already been suspected of links to the Paris attacks last November. The statement contradicted the earlier remarks from prosecutors that he had no known terror links.

According to the Belgian prosecutor, a judge issued an international and EU arrest warrant against Khalid el-Bakraoui, in December 2015.

Belgium’s Interior Minister Jan Jambon and Justice Minister Koen Geens offered this week to step down over mistakes in the investigations.

“I offered my resignation. Mr. Geens too. They were refused. We continue,” Jambon told Le Soir on Thursday. “There are two sorts of errors: At the level of justice and the level of the liaison officer in Turkey, which impacts the departments of interior and justice. But now, we continue to do our jobs.”

Tara Palmeri contributed reporting to this article.

This story was updated to reflect a statement Friday from the prosecutor's office.