More than 250,000 people have been evacuated in northeast China following serious floods that have already left four dead and forced the relocation of thousands in neighbouring North Korea.

Heavy summer downpours have dangerously swollen the Yalu River, which forms the border between the two countries, and forecasters are warning of yet more torrential rain to come. Chinese officials said yesterday that 253,000 people had been evacuated in Liaoning province in less than 24 hours due to the rains, as the nation struggles with its worst floods in a decade.

In Dandong city alone, which borders North Korea, more than 94,000 residents were evacuated and some power and transport links were cut off, the official Xinhua news agency reported.

A couple in their 70s and a mother and son died in Kuandian county, around 100 kilometres northeast of Dandong, when flash floods swept away their homes, Xinhua said, citing a local flood control official.

A 60-year-old man was also missing in Kuandian after his house collapsed in a rain-triggered landslide, but no new casualites were reported yesterday.

At one stage on Saturday water levels at a Dandong monitoring station rose to 2.5 metres above the warning line, the second highest since records began in 1934, according to Xinhua.

Photos showed helicopters airlifting people from damaged rooftops as grey water swirled around buildings.

China’s national meteorological centre warned on Sunday that new downpours were expected in parts of Liaoning, including Dandong, for another 24 hours at least.

In neighbouring North Korea, more than 5,000 people have been moved to safety after parts of Sinuiju city and rural communities near the border were “completely inundated”, the official Korean Central News Agency said.

Traffic in downtown Sinuiju was “paralysed” and flood victims were stranded on rooftops and on hills, prompting the North’s leader Kim Jong-Il to order an emergency military rescue operation, it added.