The rods at North Korea's Yongbyon atomic complex can be used at the South's nuclear power plants, he said in a briefing for domestic reporters.

"Details of the purchase plan will be discussed at the six-way talks," the unidentified official was quoted by Yonhap news agency as saying.

The North agreed last year in landmark talks to disable nuclear plants at Yongbyon under a deal reached with the United States, China, Japan, Russia and South Korea.

But disputes over Pyongyang's declaration of nuclear activities due last December 31 have delayed the permanent dismantling of the plants and the handover of all nuclear material.

Seoul's chief nuclear envoy, Kim Sook, said Wednesday that North Korea plans to blow up the cooling tower in Yongbyon to symbolise its commitment to nuclear disarmament.

The tower will be toppled soon after the North hands over the declaration of its nuclear activities, he said on his return from talks in Washington with his US and Japanese counterparts.

Hopes are growing that the impasse will soon end since the North this month gave the United States 18,000 pages of operating and production records for its Yongbyon reactor and reprocessing plant.

These produced weapons-grade plutonium, including the material which the North used to stage a nuclear test in October 2006.

In return for total denuclearisation, the North would receive energy aid, a lifting of US sanctions, the establishment of diplomatic relations with Washington and a formal peace treaty with the United States.

Washington is expected to start the process of removing the North from its list of terrorism-sponsoring states following the destruction of the cooling tower.