Unification Minister Lee Jong-seok has rejected North Korea's demand that former South Korean President Kim Dae-jung make his visit to Pyongyang via direct flight.

Lee on Thursday told a news conference that he is not pessimistic that Kim cannot go to Pyongyang via inter-Korean railway.

The two sides are discussing an alternative that Kim travel to the North's border city of Gaesong by train and then reach Pyongyang in a passenger car.

A train ride from Gaesong to Pyongyang would take many hours, and South Korean diesel locomotives cannot operate on the North Korean section of the inter-Korean railway that runs on electricity.

In two days of talks on Kim's visit slated for next month, the two Koreas failed to agree on transportation and the size of his entourage.

The two sides will hold a second round of working-level talks in Gaesong on May 29th.