The federal prosecutor's office said Saturday that the two were taken into custody in raids overnight.
"One man was arrested in (the eastern town of) Verviers and another man in Tournai," said Eric Van der Sypt, a spokesman of the two towns.
Van der Sypt denied the two have direct links to reports of attempted attacks on a Euro 2016 fanzone.
"It is too soon to talk about a terror attack. The two men have to be questioned first," he said, adding that no weapons, explosives or other materials were found.
Belgium still grapples with the aftermath of the attacks in Brussels' busy metro system, which killed 32 people. Daesh, a militant group based in Iraq and Syria, claimed the attacks, which police said were linked to shootings and explosions in the French capital, Paris, in November 2015. Those attacks in Paris claimed 130 lives.
However, a local website said Saturday that the man arrested by police in Verviers was planning an attack on fans watching Belgium's next Euro 2016 game against Hungary on Sunday. Three men were arrested and charged last week with police saying they attempted "terrorist murder."
Police also detained 40 people in the June 17-18 raids in Brussels and across the country. No arms or explosives were found in those raids but officials said they were carried out due to the need for "an immediate intervention."
Belgian Prime Minister Charles Michel has promised "additional and updated security measures" during the time the country remains in a state of emergency.
"We want to continue living normally," Michel said after the raids in mid-June.
The tightened security in Belgium comes as its neighbor France, which hosts Euro 2016 games, is on maximum alert.
