Dozens of South Korean villagers evacuated to a temporary shelter Saturday following a toxic chemical leak in the southeastern city of Gumi as officials assessed the extent of the damage.

About 70 elderly residents left their village Bongsan in Gumi by two buses to neighbouring Baekhyeon six kilometres (3.7 miles) away, to avoid the fallout from the September 27 leak of around eight tonnes of hydrofluoric acid.

"We decided to get out of this village to avoid health risks," village leader Park Myung-seok told journalists, demanding local government authorities provide them with proper shelters.

The village is home to about 300 people, and the disaster management office in Gumi said the remaining residents would be evacuated in stages.

People in nearby Imcheon village are also demanding evacuation, Yonhap news agency said.

According to health officials more than 600 people, including local residents and firefighters, have required treatment following the leak of hydrofluoric acid at chemical maker Hube Global's factory in Gumi.

Five people were killed in an initial explosion that led to the leak as workers were unloading acid from a tanker.

But the fallout from the incident may have been far more damaging than originally thought, and a 26-member team of experts and government officials began a three-day probe Friday to gauge the severity of the situation.

The hundreds treated for inhaling toxic fumes from the leak complained of nausea, chest pain, rashes, sore eyes and scratchy throats. Some of them found blood in their saliva.

Crops and fruit on more than 90 hectares (222 acres) of land have withered, and some 1,300 livestock animals have been exhibiting symptoms similar to a cold, Yonhap news agency said.

The government has considered designating the affected area as a disaster zone, which would mean residents could be eligible for financial aid, tax cuts and compensation.