A typhoon that killed more than 20 people in China, Taiwan and the Philippines had weakened to a tropical storm on Monday as it headed inland, where mines were ordered to close and over a million people had sought safety.

Tropical Storm Sepat, which had made landfall as a typhoon in China on Sunday bringing torrential rain and powerful winds, had also damaged houses, ruined crops and cut power supply lines in eastern and southern China, Xinhua news agency said.

Eleven people were killed in Zhejiang by a tornado that spun off the typhoon and wrecked houses. In Fujian province to the south, two people were killed and one was missing in a landslide.

In the southern province of Guangdong, floods spawned by the storm had killed at least five, with eight missing.

The typhoon damaged hundreds of houses, inundated thousands of hectares of crops and cut off road traffic and power supply lines in Zhejiang and Fujian, Xinhua said, adding that 3.5 million people were affected in the two provinces.

Meteorologists predicted heavy rainfall would continue in Zhejiang, Fujian and Jiangxi until Tuesday even as the storm loses power overland.

Mines have been ordered to suspend operations in the next three days in central province of Hunan as Sepat drew near. People in low-lying regions were ordered to evacuate.

Sepat -- which takes its name from the Malay word for a species of freshwater fish -- was expected to hit Hubei Province in central China from Monday to Wednesday.

Disaster officials in the Philippines said three people drowned in flooding caused by Sepat and parts of the capital and surrounding provinces remained under water.

Taiwan's disaster centre said one person had died and several had been injured in the typhoon. About 2,500 people were evacuated and nearly 9,000 homes were still without electricity.