Former President Kim Dae-jung says Pyongyang should promptly and unambiguously move to rejoin the six-way talks.

The Nobel laureate said Seoul would never accept a nuclear North, warning of the atomic standoff's potential to spark a 'nuclear chain reaction' or arms race in Northeast Asia.

Kim expressed regret that North Korean leader Kim Jong-il has yet to fulfill his promise to pay a reciprocal visit to Seoul, stressing that such a move is absolutely crucial to prospects for improved cross-border trust and cooperation.

On Seoul's relations with Japan and China, Kim said the three countries should strive to find common ground on historical perspectives and regional cooperation, and urged Tokyo to confront and own up to its past militarism.

The former president was a guest speaker at an international academic symposium Monday marking the fifth anniversary of the June, 2000 inter-Korean summit.