Belgian police launched a "jihadist-related" anti-terrorism operation in the eastern town of Verviers, with reports saying there were three deaths, news agency AFP reports.
Public broadcaster RTBF reported three deaths and said explosions were heard at the scene, but there was no immediate confirmation.
The incident came as Europe was on high alert after 17 people were killed in the Islamist attacks on the Charlie Hebdo magazine and a Jewish supermarket in Paris last week.
"An operation is under way," a source in the mayor's office told AFP without giving further details.
Another official said separately that the incident in Verviers, which was close to the German border some 125km from Brussels, was "jihadist-related". Belgian media reported that no police were injured in the incident.
