A former U.S. ambassador to South Korea says North Korea wants the United States to resume the provision of heavy fuel oil as a condition for freezing its nuclear weapons program.

In an interview with Radio Free Asia Sunday, Donald Gregg said it is imperative for Pyongyang and Washington to make progress toward ending the 22-month nuclear dispute now, stressing that the issue should not be delayed until after the U.S. presidential election in November.

Gregg visited North Korea early this month to seek ways to ease nuclear tensions on the Korean Peninsula with North Korean officials.

Pyongyang has so far called for massive energy assistance, including 2.7 million tons of heavy fuel oil from the U.S,. in return for freezing and dismantling its nuclear facilities and materials. Such an amount of oil is five times the 500,000 tons per year that the United States had shipped to the North under a 1994 deal.