Professor Song Doo-yul of Germany's Muenster University presented himself on Tuesday to the nation's top intelligence agency for interrogation on suspicions he is a member of the powerful Politburo of North Korea's ruling Workers Party.

Song departed Academy House, his temporary residence in northern Seoul, Tuesday morning for an unidentified place, accompanied by his lawyer.

The South Korean-born philosophy professor, who returned home Monday after 37 years of exile in Germany professed to be unconcerned about the NIS interrogation.

Song is among scores of dissidents that were invited to return home from abroad for the first time in decades to attend a forum on democracy organized by the Korean Democracy Foundation.