Brussels remained on high alert Monday for a third consecutive day, with the subway closed and schools shuttered as police questioned 21 people taken into custody during anti-terrorism operations.
Sixteen people were detained on Sunday evening during a major sweep in the Belgian capital and the southern city of Charleroi, carried out amid warnings that a terrorist attack may be imminent in Brussels.
There are fears that a key suspect in the November 13 shootings and bombings in Paris may be hiding in Belgium.
Five more people were taken into custody during a new round of police searches in the regions of Brussels and the eastern city of Liege, prosecutors said Monday.
While no weapons were recovered, police found 26,000 euros (27,621 dollars) during one of the searches, the federal prosecutors’ office said in a statement.
“All items seized during the house searches are currently being examined,” it said.
A magistrate was expected to start deciding later Monday whether those detained should remain in custody.
The most-wanted suspect is believed to remain at large, however.
Police have spent a week looking for 26-year-old Salah Abdeslam, a French resident of Brussels who is believed to have taken part in the Paris terrorist attacks. He was reportedly brought back to the Brussels area by two acquaintances.
Some media reported that he may have fled to Germany, travelling for part of the way in a BMW.
Prosecutors said that BMW vehicle had fled from police on Sunday in the region of Liege, but that it was later identified and that “there is no link at all with the ongoing operation.”
Belgium’s coordinating unit for threat analysis, known as OCAM, is expected to review the security situation in Brussels later Monday and decide whether to maintain the terrorism alert level at its maximum level of 4, which indicates a “serious and immediate” threat.
Interior Minister Jan Jambon told the broadcaster VRT on Monday morning that the police operation “is not over.”
Prime Minister Charles Michel said Belgian authorities had feared that an attack similar to the one in Paris could take place in Brussels. Multiple suspects in the Paris killings had ties to the Belgian capital.
The threat level had first been raised to 4 on Saturday, leading to the closing down of markets and shopping centres, while residents were advised to avoid high-traffic areas such as stadiums and train stations.
Some Brussels-based businesses and organizations advised their employees to work from home on Monday. The EU institutions and the NATO headquarters opened, though with reinforced security measures.
“The Belgian authorities have confirmed to us that there is no specific risk or threat against the European institutions,” European Commission spokesman Margaritis Schinas said.
The threat level in the rest of Belgium has remained at 3, which means an attack is “possible and likely.”
No information has been released on specific threats. Over the weekend, police were said to be looking for two suspected terrorists who could be armed.