The accord led to the disablement of North Korea's key nuclear facilities, including the demolition of a cooling tower, the Unification Ministry said Friday.

This week's shipment included 600 tons of round steel bars. Seoul has so far provided assistance worth 124,000 tons of heavy fuel oil, ministry officials said.

The denuclearization accord, signed Feb. 13, 2007, calls on South Korea, the United States, Japan, China and Russia to provide 1 million tons of heavy fuel oil or equivalent assistance to the North, the Yonhap News Agency said.

In return, Pyongyang was required to shut down and then disable its key nuclear facilities.