More than 70,000 people displaced by severe flooding in North Korea nearly a month ago are urgently in need of supplies and shelter before winter sets in, a Red Cross official in Pyongyang said Wednesday.

The floods were caused by a typhoon that hit the country's northernmost province late last month. Officials estimate that more than 130 people died and another 400 are missing. Typhoon Lionrock, amplified by a low-pressure system in the area, created floods that submerged, severely damaged or destroyed 30,000 homes and displaced 70,000 people.

"The disaster was pretty horrendous for the people affected," Chris Staines, head of International Federation of Red Cross and Red Crescent Societies in North Korea, said in an interview with The Associated Press. "About 600,000 people have some level of immediate effect from the disaster."

The Red Cross is seeking $15.5 million to provide emergency assistance to the disaster zone over the next 12 months.

Staines said extensive damage to roads and railways caused delays in getting supplies to the disaster zone. He said that has improved and the flow of supplies, workers and building materials is accelerating. But he said more work needs to be done urgently.

"The big pressure right now is about winter," he said. "By the end of next month, it will be sub-zero overnight and within two months it will be into the minus 10s, minus 20s, middle of winter minus 35 or more. So people are really at great risk."

Staines said the natural disaster could be followed by another calamity — a health disaster — if shelter and the necessary supplies don't get to those who need them quickly.

"People need to have some place that is safe and warm and dry to stay out of the winter," he said.

North Korea has launched a massive effort to rebuild the disaster zone, diverting resources from other projects around the country and sending throngs of workers, builders and soldiers to fix roads, remove rubble and lay the foundations for new shelters. Staines said officials have requested help in obtaining corrugated tin sheets for roofing the shelters, since tents and tarpaulins aren't enough to provide protection against the winter cold.

"The (North Korean) government has mobilized enormous resources," he said. "They've escalated their response as they become aware of what the problems are and how big the disaster is."

The situation has been further complicated by narrow roads, a supply chain that is stretched thin and a number of affected areas that are remote and isolated from each other.

"It's not like in one place where you can go in and fix things," he said. "It's hundreds of places where houses need to be built, clinics need to be built, supplies need to be re-established. ... It's very complicated and very logistically challenging to make it happen."

He said North Korea has been cooperative with international aid agencies, providing them with information and access to the scene.

"Obviously, there are sensitivities that they are aware of. This is the DPRK and that's the reality of existence here," Staines said, using the acronym for North Korea's official name, the Democratic People's Republic of Korea. "But within that, we certainly haven't been prevented from doing our work and it hasn't impacted our ability to help people."