Ban's meeting with Kim Yong-Nam, North Korea's ceremonial head of state and chief of North Korea's parliament, came on Thursday, on the sidelines of a Non-Aligned Movement summit being hosted by Iran.

The UN secretary general "expressed concern about the food and nutrition situation" in North Korea following flooding in June and July that inundated swathes of cropland, and an earlier dry spell, his spokesman Martin Nesirky said in a statement.

Ban saw the "humanitarian situation" in North Korea as a worry, the statement added.

It underlined $2 million in UN aid already provided, to the "sincere appreciation" of Kim.

North Korea suffered a famine in the 1990s that killed hundreds of thousands. It still struggles to feed its people even in normal times.

International aid to the reclusive state, which today is ruled by Kim Yong-Un, the grandson of North Korea's founder Kim Il-Sung, is complicated by the country's nuclear weapons programme.

The United States early this year was poised to give 240,000 tonnes of food aid in return for a freeze on nuclear and missile tests, but the plan was scrapped when Pyongyang conducted an abortive rocket launch in April.

The UN nuclear watchdog on Thursday released a report saying North Korea's nuclear programme was a matter of "serious concern," adding that statements about uranium enrichment and a light-water reactor under construction "continue to be deeply troubling."

The North has staged two nuclear tests, in 2006 and 2009.

Ban, a former South Korean foreign minister, also said he hoped that relations between Seoul and Pyongyang would improve, and said such a rapprochement "could also help the North improve ties with the United States," the statement said