Seoul - South Korea's point man on North Korea has offered to resign, government officials said on Wednesday, in what may be a major reshuffle of the national security team triggered by Foreign Minister Ban Ki-moon's departure.

The shake-up comes as South Korea considers its next steps after North Korea conducted its first nuclear test on October 9.

President Roh Moo-hyun said after the test business will not be as usual and Seoul was reassessing its policy of engagement with the North.

Unification Minister Lee Jong-seok offered to resign on Tuesday and was firm about his decision, a ministry official said. South Korean Defence Minister Yoon Kwang-ung has also offered to resign, a Blue House official said on Tuesday.

Vice Foreign Minister Lee Kyu-hyung indicated that the moves were related to Ban's departure.

"I'm not in the position to comment directly," he told reporters on Wednesday. "But since Foreign Minister Ban Ki-moon has been named UN secretary-general, the replacement of the foreign minister has been anticipated."

Ban will take over as UN secretary-general when Kofi Annan leaves at the end of this year, and is expected to step down as foreign minister in the next few weeks.

Unification Minister Lee, a North Korea expert, has been criticised for not being tough enough against Pyongyang.

But he has also been praised for managing bilateral ties with the North during a difficult time as Pyongyang took successive steps to escalate tensions, first by test-launching missiles in July and then with its nuclear device.
Any acceptance by Roh of the ministers' resignations would not imply dissatisfaction with them, another government official said on condition of anonymity.

A career academic who advocated analysis of the North's inner workings and its ideology to better understand the state, Lee had been a top adviser to Roh from the beginning of the administration in 2003 and became minister in February.

Lee personally delivered an ultimatum to the North in July that unless Pyongyang renounced provocation, there would be no more food aid from the South.

Lee publicly rebuked a high-level North Korean delegation before it stormed out of the July meeting with the threat that the South "will pay a price" for refusing an offer of protection from Pyongyang.

"Who in the South asked you to protect our safety?" Lee told the North Koreans. "It would help our safety for the North not to fire missiles or develop a nuclear programme."

It was not immediately clear whether the resignations would be accepted and when the reshuffle would take place. Ban is expected to leave Seoul for New York in mid-November.
Speculation on who might replace Ban has focused on Blue House security adviser Song Min-soon.

Neither Yoon nor Unification Minister Lee has been touted as the possible next foreign minister, and Lee was quoted on Wednesday as saying he wants to return to academic life.

"The job of reshuffling the national security portfolio would take about two weeks," another government official quoted Roh's chief of staff as saying.