Prosecutors say the German owner of the popular YouPorn and Pornhub websites has been arrested on suspicion of tax evasion.

Fabian Thylmann was arrested last week on a German warrant and is currently in custody in Belgium, where he lives. Ulrich Bremer, a spokesman for prosecutors in Cologne, said Tuesday that several properties including his home were searched last week.

Bremer says it isn't clear when Thylmann might be extradited to Germany. He could not say whether anyone else is under investigation or give further details of the case.

YouPorn and Pornhub are among the 110 most popular sites on the planet, according to Web information company Alexa.