Storm Muifa triggered heavy rains in Shanghai as it passed by the city [Reuters]

Workers at a chemical plant in China are scrambling to protect the facility after waves from a powerful tropical storm breached coastal defences, the state news agency Xinhua reports.

Tropical Storm Muifa is barrelling towards the northeastern province of Liaoning, where it was expected to make landfall later on Monday after being downgraded from a typhoon.

Xinhua said people living near the Fujiahua chemical plant in Dalian, a city in Liaoning, were being evacuated after the dyke protecting it from the sea was breached on Monday morning.

Soldiers and workers with forklift trucks were involved in the effort to prevent sea water from creating a spill of toxic chemicals from the plant, the report said.

"Liaoning is likely to see winds gusting in excess of 60 miles per hour as Muifa makes landfall at 12 GMT on Monday", Al Jazeera weather forecaster Richard Angwin said.

"These onshore winds will be accompanied by a storm surge which will add to the threat posed to the dykes protecting the chemical plant."

Thousands evacuated

Tens of thousands of people living along China's east coast were evacuated over the weekend as Muifa approached, amid fears it would hit Shanghai, the country's densely populated commercial capital.

Chinese airlines cancelled hundreds of flights and thousands of fishing boats were ordered to stay in port.

But the city was spared a direct hit, suffering only some power outages and minor damage as the storm passed by.

A serious chemical leakage would be a fresh headache for Liaoning, which recently suffered an oil spill from two offshore platforms.

Pollutants from that spill have been found spreading to beaches, and been blamed for losses to tourism and aquatic farming businesses, Xinhua reported in July.