HONG KONG - Hundreds of flights were cancelled on Friday in China's populous Guangdong province and neighbouring Hong Kong ahead of Typhoon Saola's arrival, with the powerful storm forcing some mainland cities to close businesses, schools and even financial markets.

Three tropical cyclones have formed in the northwest Pacific Ocean and South China Sea. Saola and Haikui were labelled typhoons while Kirogi, the most distant from land, was still classified as a tropical storm.

Saola, packing winds of more than 200 kph (125 mph), will make landfall in Guangdong, which encompasses Hong Kong. It could be among the five strongest typhoons to hit Guangdong since 1949, Chinese authorities warned on Thursday.

Saola could make landfall on Friday night or Saturday morning as a severe typhoon along the coast between the cities of Huidong and Taishan, China's National Meteorological Centre said. Hong Kong and Macau lie in the centre of that coastline.

Weather conditions will deteriorate rapidly as the typhoon makes landfall, the Hong Kong observatory said, with storm surge potentially reaching around 3 metres (10 feet) higher than the normal tide in some areas.

All schools in Hong Kong were closed on Friday, despite being the first day of term for many.

"We can see that the eye of the typhoon will pass very close to Hong Kong. I'm a bit concerned and hope it won't cause too many casualties," office worker Wai Yi said as she strolled by the sea with her husband in the city's eastern Heung Fa Chuen area.

In Hong Kong on Thursday, crowds were seen jostling at fresh food markets in downtown Wan Chai district with many vegetables already sold out. There were long queues at supermarkets as people stocked up ahead of the storm.

The city's flagship carrier Cathay Pacific said all flights in and out of Hong Kong between 2 p.m. (0600 GMT) on Friday and 10 a.m. (0200 GMT) on Saturday have been cancelled.

DESTRUCTIVE WINDS

Authorities suspended all trains in and out of Guangdong province from 8 p.m. (1200 GMT) Friday to 6 p.m. (1000 GMT) Saturday.

The cities of Shenzhen and Guangzhou had already closed schools.

Shenzhen went a step further, suspending work, businesses and financial markets from Friday afternoon, warning of potentially destructive winds lashing the city of more 17 million people through Saturday.

"Of course I'm worried, it's forecast to be a big one and I want to get home," said a delivery driver surnamed Lu between puffs of a cigarette, during a busy day for supermarkets in Shenzhen as many were set to close early.

By 10:55 a.m. (0255 GMT) Friday, the airports in Shenzhen and the nearby city of Zhuhai had cancelled hundreds of flights.

As a safety precaution, the Hong Kong-Zhuhai-Macau Bridge connecting the three cities would be closed from 3:30 p.m. (0730 GMT) on Friday.

The Taishan Nuclear Power plant in Guangdong said it had halted outdoor operations and transferred vulnerable materials from the plant. Emergency staff are on duty and all personnel and facilities at the base are safe, it said.

Macau's Weather Observatory said it would raise its wind warning level to Signal 8 by 2 p.m. on Friday, and could raise it to the highest Signal 10 early on Saturday morning.

Meanwhile, Typhoon Haikui is approaching Taiwan and expected to make landfall on the northern part of the island on Sunday before heading towards the southeastern Chinese city of Fuzhou, according to Taiwan's Central Weather Bureau.

(Reporting by Farah Master and Joyce Zhou in Hong Kong, David Kirton in Shenzhen, Bernard Orr, Ryan Woo, Ethan Wang in Beijing and the Beijing newsroom; Additional reporting by Ben Blanchard in Taipei; Editing by Lincoln Feast, Raju Gopalakrishnan and Simon Cameron-Moore)