The state prosecution on Tuesday demanded a 15-year prison term for Korean-German scholar Song Du-yul on charges of spying for North Korea.

Prosecutors said during a trial at a Seoul court that they requested the heavy sentence for Song, professor of Muenster University in Germany, accusing him of violating the anti-communist National Security Law.

Prof. Song, 59, was indicted last November for acting as a member of the decision-making Politburo of North Korea’s Workers Party and spreading the North’s Juche, or self-reliance ideology abroad on orders by Pyongyang.

He has been on trial since last December after three-month investigations into his alleged connections with communist North Korea. He returned to South Korea in September last year after spending decades in self-imposed exile.

In a written statement submitted to the court, Song pleaded for leniency and said ``the National Security Law is an obstacle to Korean unification and the law even falls behind the standards of laws made in the mid-17th century.’’

Song is accused of visiting North Korea more than 20 times since 1973 and receiving up to $104,000 from the North.

The prosecution also accused Song of attempted fraud by filing a suit against Hwang Jang-yop, a former secretary of North Korea's Workers Party who defected to South Korea in 1997, to seek compensation for Hwang's insistence in a book that Song was an alternate Politburo member under the pseudonym Kim Chol-su.

Song’s lawyer also condemned the prosecution’s move by saying, ```It seems like we are sitting in a courtroom in the 1970s. We cannot help but raise doubts of what kind of country we are in.’’

The local court is scheduled to hand down a verdict on Song on March 30.

During investigations, Song admitted that he had joined the Workers’ Party in 1973 and received thousands of dollars from Pyongyang but had continued to deny accusations that he had been formally elected as a Politburo member or participated in activities benefiting the North while residing in Europe.