"About 4,000 people are now listed as missing, and we expect the final toll of dead and missing to reach 10,000," said the independent aid group Good Friends.

North Korea's official media has admitted that hundreds of people were dead or missing after a severe typhoon followed by heavy rain hit the country on July 10.

Good Friends, a long-term aid partner for North Korea, declined to reveal the sources for its figures. Other international aid agencies have given lower numbers, based on official North Korean statistics.

Serious flooding helped trigger a famine in the mid-1990s in which aid groups claim some two million North Koreans died.

A decade later the country is still unable to feed its people and damage to farmland from the latest flooding has sparked concerns that chronic food shortages may worsen again this year.

North Korea's bare hillsides, stripped of tree cover by impoverished residents looking for fuel, are particularly vulnerable to flooding and landslides caused by erosion.

Two weeks of heavy rainfall sent rainwater sweeping down deforested hillsides, unleashing rivers of mud on farms and villages.

A South Korean expert said energy and food shortages were behind the deforestation as North Koreans seek firewood and try to farm hillsides.

"North Korea began developing mountainside farming from the 1970s in an effort to boost food production," said Kwon Tae-Jin of the Korea Rural Economic Institute.

"But that just aggravated the food shortage and made the country very vulnerable to heavy rains."

Worst-hit areas include Sinyang and other counties along the upstream of the Taedong river which runs through the center of Pyongyang, leaving thousands of people dead or missing, the aid group said.

In Haeju, 105 kilometers (90 miles) south of Pyongyang, witnesses saw 200 bodies fished out of floodwaters, Good Friends said.

Malaria was now spreading in southern regions, the group added.

Though a massive relief operation was under way, Good Friends said that North Korea's army was confined to barracks because of tension with the outside world over its recent missile tests.

The missiles shot on July 5 triggered condemnation from the international community and weapons-related sanctions from the United Nations.

Angry South Korea suspended rice and other humanitarian aid to the communist North just days before the typhoon hit.

South Korea's former unification minister Jeong Se-Hyun, who is now leading the non-governmental Korean Council for Reconciliation and Cooperation, said North Korea was in crisis but felt it was in no positon to request aid after defying the international community over its missile launches.