Belgian authorities have closed a national park near the Dutch border as the search for a heavily armed soldier with far-right views continues.
Dutch and German police are supporting the hundreds of Belgian officers and soldiers involved in the manhunt.
The suspect, a military shooting instructor named as Jurgen Conings, went missing on Monday after taking weapons from a barracks.
He is said to have made threats in the past against a top Belgian virologist.
Marc Van Ranst, who led Belgium's public health response to coronavirus, has been taken to a safe place with his family.
The Belgian federal public prosecutor's office has said it believes the suspect is still alive.
On Thursday, Defence Minister Ludivine Dedonder said the suspect had been identified by Belgian military intelligence for suspected ties to the far right as early as 2019. Last summer, the ministry filed a complaint against him for racist comments he posted online.
"As soon as these behaviours appeared, this soldier should no longer have had access to these weapons and should have been subject to stricter controls," the minister said.
She has also pledged stricter measures against serving of former members of the military who post hate speech or racist views online, from limiting their access to weapons, to suspension or dismissal from the army.
In addition to support from abroad, 250 Belgian police officers and 150 soldiers are involved in the search, according to prosecutor Wenke Roggen.
The operation is currently centred on the Hoge Kempen national park, a 12,000-hectare area (46 sq miles) of forest and heathland, not far from the Dutch border.
The vast area is normally open for hiking, cycling, horse riding and overnight stays, with Belgian newspaper Het Laatste Nieuws describing it as "the only place in Flanders [the Dutch-speaking northern region] where you can really get lost".
The park has been closed since Wednesday as part of the search, while reports say several barracks have been closed and soldiers barred from leaving.
Dutch and German police have also been placed on alert in case the suspect tries to cross the border, according to Belgian media.
Police have appealed to the public not to approach the man but to get in touch if he is spotted. Authorities say he represents the highest level of threat on their scale of four and may have plans to attack either individuals or institutions.
A car said to belong to the soldier containing four anti-tank rocket-launchers and ammunition was found on Tuesday. But police believe the suspect is still armed with other guns, including a sub-machinegun, and carrying a bulletproof vest.
Reports described the soldier as a "potentially highly violent extremist". He is said to have left letters indicating he is prepared for a deadly battle with police and "could no longer live in a society where politicians and virologists have taken everything away from us".
The suspect has in the past threatened Mr Van Ranst, considered Belgium's best-known virologist.
Justice Minister Vincent Van Quickenborne told Flemish TV there were indications that Jurgen Conings was "violent and in the course of the past 24 hours, evidence has emerged the man poses an acute threat".