The death toll from flooding in a North Korean border region now stands at 133 with tens of thousands homeless in what the United Nations has called a disaster "beyond anything experienced".

Around 107,000 people have abandoned their homes around the Tumen River area, the UN said, citing Pyongyang government figures. The torrential rain along the north-east border with China and Russia is the worst for decades, according to local officials.

"The scale of this disaster is beyond anything experienced by local officials," said UNICEF deputy representative in North Korea Murat Sahin, who witnessed the devasted area last week, according to France24.

"Although the early warning system was triggered, the scale of the damage was unexpectedly high."

Shelter and food supplies are in urgent need for families, with humanitarian aid required to take effect before the onset of winter when temperatures fall below zero degrees. A priority is to rebuild 20,000 houses by the beginning of October.

"Families here lost everything. We met the household doctor for the community in the rubble of her clinic," Sahin added. "She told us that 11 out of 15 pregnant women in the community had miscarriages since the floods."

North Korea is prone to natural disasters, particularly floods, which is due to deforestation and poor infrastructure. North Korea's mountainous regions have been hacked back for fuel or transformed into terraces of ricefields. As a result, rainwater has poured down hillsides unimpeded.

The country's desperate food shortages are predicted to become more severe when "most households were already estimated to have poor or borderline food consumption levels", the UN Food and Agriculture Organisation said in a statement.

"Tens of thousands of dwelling houses and public buildings collapsed and railways, roads and other traffic networks and power supply system, factories, enterprises and cultivated lands were destroyed or submerged," said a statement the Korean Central News Agency's website.