China battled Monday to avert a disaster at a chemical plant on its northeast coast as a severe tropical storm that has killed three people in South Korea approached.

Workers were rushing to repair a dyke protecting a chemical plant after it was breached by high waves in the province of Liaoning, where the storm was expected to make landfall later Monday.

Residents near the Fujia Group plant in the port city of Dalian were evacuated as a precaution, the state Xinhua news agency said in a report confirmed by an official with the Liaoning border police.

The official, who refused to be named, would not provide further details when contacted by AFP.

Authorities did not say which chemicals were in danger of spilling from the plant, which makes paraxylene -- a flammable, carcinogenic liquid used in the production of polyester films and fabrics, Xinhua said.

Torrential downpours and high winds unleashed by Muifa -- which was a typhoon before it weakened to a severe tropical storm -- have already wreaked havoc along China's eastern coast, as well as neighbouring South Korea.

Airlines cancelled hundreds of flights and thousands of fishing boats were ordered to stay in port over the weekend as Muifa approached. It had initially been due to hit Shanghai, but changed course and travelled north instead.

The storm drenched the eastern province of Shandong, where more than 100,000 people were moved to safety, local authorities said.

US oil giant ConocoPhillips was also forced to suspend clean-up operations on a two-month-old oil spill in Bohai Bay off the coast of Shandong due to the storm, the firm said in a statement.

"Clean-up activities will resume as soon as it is safe to do so," it added.

Muifa also left three people dead and one missing as it battered nearby South Korea with strong rain and winds that toppled hundreds of power lines, signposts and trees.

Power was cut to 320,000 houses in southwestern provinces, while roads, port facilities and breakwaters were destroyed in dozens of locations.

A 76-year-old fisherman was found dead Sunday on the southern South Korean island of Wando. A man in his 40s drowned after being swept away by stormy seas in the southern port of Busan.

A 50-year-old woman was found dead Monday after falling into a flooded stream in Hwasun in the southwest and a 65-year-old man was reported missing in Busan.

Muifa is also due to hit North Korea -- which neighbours Liaoning province -- on Monday night.

The impoverished state is still reeling from summer downpours and floods that have killed 30 people, destroyed more than 6,750 houses and inundated more than 48,000 hectares (120,000 acres) of farmland.

Authorities in Dandong, a border city in Liaoning, have set up more than 750 temporary shelters that are capable of accommodating more than one million people, Xinhua reported.

Thousands of soldiers are also on standby to conduct rescue and relief work after the storm passes, it said.

Muifa has already destroyed nearly 170 houses and caused damage worth 1.9 billion yuan ($290 million) in the eastern province of Zhejiang, where one person went missing over the weekend after a boat sank.

But so far, the storm has not caused as much damage as initially feared.

Authorities had expressed concern that Muifa could cause destruction similar to that unleashed by Typhoon Saomai in 2006, which was the worst to hit China in 50 years and killed at least 450 people.