Typhoon Usagi killed at least 25 people after crashing ashore in southern China, throwing the region's transport systems into chaos and leaving tens of thousands of airline passengers stranded in Hong Kong on Monday.

Schools and businesses were shut as activity in the normally teeming financial hub slowed to a crawl after Usagi punched a long swathe of Chinese coast with torrential rain and winds of up to 165 kilometres (103 miles) per hour during the night.

The deaths were reported by Chinese state media after Usagi -- which meteorologists say was the world's most powerful storm this year -- made landfall in Guangdong province northeast of Hong Kong on Sunday evening, prompting the highest level of alert from the National Meteorological Center.

The reports by Xinhua news agency and CCTV did not say how the 25 people were killed but said all the deaths were in Guangdong after the typhoon brought down trees and damaged roads.

Bullet trains from Guangzhou city to Beijing were suspended and Xinhua said that winds were strong enough near Shanwei to blow cars off the road. More than 47,000 fishing boats were in harbour and schools were closed in 14 coastal cities.

Usagi had previously killed two people in the Philippines and unleashed landslides and power outages across southern Taiwan at the weekend as it ploughed through the Luzon Strait with ferocious winds and heavy downpours.

Monsoon rains exacerbated by Usagi brought flooding on Monday to the Philippine capital Manila and nearby provinces.

As the typhoon bore down on Hong Kong, operators shut down one of the world's busiest sea ports and nearly 450 flights were either cancelled or delayed as Cathay Pacific and other airlines imposed preemptive suspensions.

Strongest typhoon for years

The Observatory said it was the strongest typhoon to brush Hong Kong since 1979. Tens of thousands of people had their travel plans upended with ferries and trains also disrupted, while Cathay said it expected flights to start resuming only from noon (0400 GMT) on Monday.

Many passengers were milling around Hong Kong airport hoping to rebook their flights, but hand-written signs in Chinese and English warned them that there was little chance of getting standby seats on flights out Monday and to check back later.

Officials in Hong Kong, which is well versed in typhoon preparations, said that 13 people were injured during the storm, while more than 60 trees had fallen.

Major thoroughfares were empty and signboards swayed in the wind early Monday, but some residents ignored official warnings and headed out to the coastline in raincoats to brave the wind.

"I heard the typhoon was strong so I wanted to feel it," one woman told Cable TV in the eastern town of Ma On Shan.

The storm made landfall at 7:40 pm (1140 GMT) on Sunday near Shanwei, sparing densely populated Hong Kong a direct hit.

On its way towards southern China, Usagi forced the evacuation of 3,400 people in southern Taiwan. A mudslide hit one hotel in a popular hot-springs resort area of Taitung county late Saturday, shattering windows and damaging furniture.

Twelve people were injured in Kinmen, a Taiwan-controlled island off China's Fujian province, after they were hit by falling trees, according to the Central Emergency Operation Centre.

Prior to hitting Taiwan, Usagi brushed the far north of the Philippines where a man and a woman drowned on Friday when their boat capsized in high seas. Another three people remain missing.

"Local disaster officials told us this was the strongest typhoon they had experienced in years," regional civil defence officer Ronald Villa told AFP on Sunday.

Typhoon Bopha left a trail of destruction in the southern Philippines last year, triggering floods and landslides that left more than 1,800 dead and missing and displaced nearly one million people.