The fee North Korea charges South Korean flights for passing through its air space is five times higher than what the South charges foreign fliers.

Citing a document from the Ministry of Land, Transport and Maritime Affairs, Grand National Party Lawmaker Chung Hee Soo said the national flag carriers -- Korean Air and Asiana Airlines -- paid Pyongyang an average of 720-thousand won, about 630 U.S. dollars, per flight from 2002 to May 2008. In other words, they paid about 14-point-two billion won to the North.

In comparison, South Korea charged about 150-thousand won per passage to foreign airliners and earned 21-point-four billion won during the same period.

Chung said that Seoul should discuss the lowering of the fee with Pyongyang through inter-Korean working-level aviation talks.