Super Typhoon Usagi, the most powerful cyclone of 2013 so far, was closing in on Taiwan and the Philippines on Saturday, packing gusts of nearly 300 kilometres (185 miles) per hour and bringing storm surge and torrential rain.

Usagi, which intensified dramatically into a super typhoon in the early hours of Friday, is to roar through the Luzon Strait dividing the Philippines and Taiwan on Saturday morning as it barrels towards Hong Kong and the Chinese coast.

Taiwan's southern tip is set to be clipped by the storm's northeast quadrant, typically home to a tropical cyclone's most powerful winds.

The US Navy's Joint Typhoon Warning Center said in a bulletin issued at 11.00 pm Friday (1500 GMT Friday) that Usagi was packing sustained winds of 130 knots (240 kph, 150 mph), with gusts of up to 160 knots (296kph, 185mph), making it the equivalent of a strong category four Atlantic hurricane.

"It is the strongest typhoon in the west Pacific region this year," a weather forecaster at the Taiwan Central Weather Bureau told AFP on Friday. Meteorologists have described Usagi as the most powerful tropical cyclone to form in 2013 so far.

The bureau said in a bulletin early Saturday that the storm was moving west northwest at 19 kilometres an hour.

Taiwan's defence ministry Friday deployed more than 1,600 soldiers in "high risk" areas prone to flooding and landslides while placing 24,000 others on standby.

Philippine authorities on Friday evacuated some 240 people in the northern agricultural province of Tarlac, while ferries were restricted to their ports, stranding travellers.

A signal four alert was issued for the Batanes island group in the extreme north of the country, warning large trees could be uprooted, plantations flattened and power and communications infrastructure knocked out.

Emergency relief services were also put on heightened alert, with the Red Cross already stockpiling first aid kits and food packs in some areas.

"Damage to affected communities can be very heavy," the Philippine Atmospheric, Geophysical and Astronomical Services Administration said. "The situation is potentially very destructive to communities. All travel and outdoor activities should be cancelled."

The country's National Disaster Risk Reduction and Management Council said Usagi would cause intense rainfall of 10-20 millimetres per hour within a 700-kilometre range.

In China, nearly 23,000 fishing boats took shelter in Fujian province ahead of the storm, state media reported early Saturday, while more than 4,000 people living in coastal fish farms were evacuated.

China's meteorological authority upgraded its warning for the typhoon to orange, the second highest, state news agency Xinhua said late Friday.

Hong Kong officials warned of worsening weather in the southern Chinese territory.

"Weather will deteriorate significantly with strengthening winds and rough seas," the Hong Kong observatory said. Its tropical cyclone track map showed the storm would hit the city after 8:00 pm (1200 GMT) on Sunday.

The typhoon is expected to be downgraded to "severe" by the time it makes landfall in the territory, according to the observatory -- still enough to stop metro and ferry services and curtail air travel.