The typhoon had already killed 36 people in the Philippines as it triggered widespread flooding [AFP]

Typhoon Megi, the strongest storm to sweep through the northwest Pacific in two decades, has weakened and been downgraded to a strong tropical storm.

The typhoon had hit southern China, bringing torrential rains and powerful winds that prompted officials to shut down public services across the region.

Flood control authorities evacuated some 160,000 people from the coastal Fujian province to safety ahead of the typhoon, the official Xinhua news agency said.

State television broadcasted images of gales bending trees and toppling billboards, as large waves whipped the coast. Roads were also flooded in the city of Zhangzhou.

The main airport in the coastal city of Xiamen cancelled 79 flights due to the typhoon. Authorities also stopped ferry services throughout the province. 

Weather warning

China's national meteorological centre had earlier confirmed that the typhoon had reached the Asian country's coast and advised people to avoid going out.

"If you are already outside, do not shelter from the rain near temporary structures, billboards, iron masts and trees," it said in a statement.

But the intensity of the typhoon, which was initially feared to be among the worst in 50 years to hit China, weakened as it reached the province.

Megi had already swept through the Philippines earlier in the week, killing at least 36 people as it caused widespread flooding. In Taiwan it brought record-high rainfall that triggered massive landslides leaving at least 12 people dead.

Taiwanese rescuers are still searching for about two dozen missing people who are thought to have been buried beneath the landslides.

Typhoons regularly hit China, Taiwan, the Philippines and Japan in the second half of the year after gathering strength from the warm waters of the Pacific Ocean or South China Sea.