Belgian prosecutors said a flag of the so-called Islamic State group and a jihadist manual were found beside the body of an armed suspect who was shot dead during an anti-terrorist operation in Brussels yesterday.
The dead man has been named as 35-year-old Mohamed Belkaid, an Algerian living illegally in Belgium.
Belgian federal prosecutors say two people have been detained but it is not clear if they are connected to the shooting.
One of those detained was taken to hospital with a broken leg.
Brussels police killed Belkaid, who was armed with an assault rifle, after four officers were wounded yesterday during what investigators had expected to be a routine search on an apartment in the south of the Belgian capital.
Two other people escaped.
Mr Michel told RTL radio that police planned further operations in the coming hours and days.
"The threat remains," Mr Michel said, adding that Belgium would review its level of alertness and consider possible extra measures during the day.
Brussels was entirely locked down for days shortly after the Paris attacks on 13 November last year for fear of a major incident there.
Several of those involved in the shootings and suicide bombings, claimed by the so-called Islamic State, were based in the city.
Brussels has maintained a high state of security alert since then, with military patrols a regular sight.
Police searched nearby buildings through the night in the Brussels borough of Forest.
Investigators believe much of the planning and preparation for the Paris assault was conducted in Brussels by young French and Belgian nationals, some of whom fought in Syria.
One of the prime suspects, 26-year-old Brussels-based Frenchman Salah Abdeslam, is still on the run.
