Belgian police have made 16 arrests in anti-terror raids but suspected Paris attacks gunman Salah Abdeslam remains at large, the authorities have said.
A total of 22 raids were carried out on Sunday across Brussels and Charleroi, Belgian prosecutor Eric van der Sypt told a news conference.
Police fired two shots at a car during an operation in Molenbeek, injuring one suspect who was later arrested.
More than 130 people died and some 350 were injured in the attacks in Paris.
No weapons or explosives were found during the searches on Sunday, van der Sypt said.
Brussels will remain on the highest level of terror alert, Belgium's Prime Minister Charles Michel said. Universities, schools and the city's metro system will also remain shut.
Brussels has been on lockdown all weekend amid a manhunt for Abdeslam, who is suspected of being among the assailants who killed 130 people in Paris on Friday.
Michel told reporters that authorities feared "an attack similar to the one in Paris, with several individuals who could also possibly launch several attacks at the same time in multiple locations".
Meanwhile, the BBC understands that another of the suspected attackers - pictured in a new French police appeal issued on Sunday - arrived in Greece under the name of M al-Mahmod.
The BBC's Ed Thomas has matched the image released by French police with a photo on the arrival papers of a man who reached the Greek island of Leros on 3 October.
French police have asked for more information about the man, whom they say was the third suicide bomber to strike the Stade de France on 13 November.
Earlier, Belgian Interior Minister Jan Jambon said the danger to Belgium was not tied to Abdeslam alone.
"The threat is broader than the one suspected terrorist," he told Flemish broadcaster VRT.
It was not clear if Jambon was referring to those involved in the Paris attacks, or others who might be planning attacks in Belgium.
Soldiers joined police officers on patrols in Brussels over the weekend. Many public spaces in the usually bustling capital were deserted, as people heeded official warnings to avoid crowds.
Mohammed Abdeslam, the brother of Brahim Abdeslam who blew himself up in Paris and Salah Abdeslam, spoke to Belgian TV on Sunday to urge his fugitive brother to hand himself in.
The Belgian authorities have so far charged three people with involvement in the Paris attacks, claimed by Islamic State militants.
French media have reported that nine militants carried out the attacks, and seven died on Friday night.