New Zealand nationals are reportedly among victims who are dead after landslides crushed their tourist accommodation in South Korea.

The Korea Times reported that a 65-year-old, her daughter, 36, and her grandson, 2, were among the 13 people who died in Gapyeong, Gyeonggi Province, amid heavy rain on Monday morning.

They were all New Zealand citizens.

A close friend of the trio told TVNZ they were believed to be dead.

"All I know at this stage is that the cafe part of their lodging was destroyed," he said.

"They were inside that building at the time. One male employee left seconds before the hill behind them came down."

Police and rescue workers reportedly said today that they recovered the bodies of three people, who were inside when their accommodation was buried.

A spokeswoman for the Ministry of Foreign Affairs and Trade confirmed it - and the New Zealand Embassy in Seoul - were responding to the reports.

More than 1000 people have been forced from their homes after days of heavy rain caused floods in South Korea. At least 13 people are reported dead with another 13 missing, authorities said on Tuesday.

Vehicles were swept away and disaster officials said more than 5751 hectares of farmland, key highways and bridges were innundated in the capital, Seoul.

President Moon Jae-in was set to hold an emergency meeting on Tuesday, after he had urged national and regional authorities to "make all-out efforts to prevent further loss of life" the previous day, Reuters reported.

In neighbouring North Korea, state media warned of possible flooding, saying that some areas were also experiencing heavy rainfall.

Citing unidentified South Korean government sources, Yonhap said North Korea opened the floodgates of a border dam on Monday without advance notice to its neighbour.