bwin.party CEO Norbert Teufelberger was questioned by Belgian police after speaking at the Responsible Gaming Day conference in Brussels, according to several media reports.
Belgium began licensing online gambling operators in 2012. bwin.party does not have a Belgian license but does operate in the country.
"In response to press reports this afternoon, the Group can confirm that Norbert Teufelberger, Co-CEO, was requested to attend an interview with the Belgium authorities," the company said in a statement. "He complied voluntarily with this request and is co-operating fully with the authorities. We will issue further details in due course."
It is unclear at this time whether Teufelberger will be allowed to leave the country or if he will be detained further.