The BBC's Juliet Hindell: "It's difficult to gauge how severe the food shortages are"

Intelligence agents in South Korea say the data comes from a rarely-publicised survey carried out by the North's communist government, which presides over one of the most isolated and impoverished countries in the world.

Correspondents say if the statistics are correct as reported by the South Korean news agency Yonhap, aid agencies fear that pervious drought and floods have left the country in a far worse situation than previously thought.

South Korea says Pyongyang residents no longer receive rations

The survey records that the population fell by between 2.5 million and 3 million from 1995 to March 1998.

South Korean sources said the survey was conducted by the Public Security Ministry before the election of delegates for North Korea's parliament, the Supreme People's Assembly, last July.

The North's security ministry has also predicted further population losses unless food shortages are alleviated.

Starvation and disease

The sources attributed the population loss mainly to starvation and disease but said migration also played a part.

South Korean intelligence officials were not available for comment. But they have estimated North Korea's current population at about 24 million.

Many are reported to be surviving on roots and grass

Figures provided to the UN Development Program by the North estimated its population at 21.7m in 1995, 22.64m in 1998 and 22.94m in 1999.

There have been conflicting reports on the severity of North Korea's food crisis. But defectors and international agencies have raised the possibility that more than 2m North Koreans have died of famine and disease since 1995.

Correspondents say the figures may help the North in obtaining more international food aid.

Deaths foretold

US and South Korean sources who have visited the North say 10% of the North's population may have died as a result of starvation and malnutrition in the past three years.

With its food shortfall estimated at least 1.63m tonnes this year, North Korea has launched a desperate campaign to boost agricultural production.

Kim Jong-Il, who was confirmed as the North's supreme leader last year, has branded agricultural production as the country's "most important" task, reflecting the depth of the food shortages.

Threats and brinkmanship

Leader Kim Jong-II says agriculture is the main priority

South Korean newspapers claim North Korea stopped the distribution of food rations to residents of the capital Pyongyang in January.

Analysts in Seoul believe that North Korea may be coming under increased US pressure to improve ties with its southern rival before it gets any new food aid.

Pyongyang has routinely used threats, promises and nuclear brinkmanship to extract aid and concession from the United States and its allies.

The North has been negotiating with Washington for additional food aid to help fend off starvation this year.