Taipei - Evacuations were stepped up in Taiwan Monday as 'super typhoon' Dujuan swirled towards the island, gathering strength on its approach to the east coast.
Torrential rains and high winds are forecast across Taiwan from Monday afternoon, with landfall predicted around 11:00 pm.
Crashing waves were already battering the northeastern coast by midday and fishing boats have been called back to shore.
Taiwan's weather bureau upgraded Dujuan to a "strong typhoon" Sunday - its top category.
Other regional weather bureaus, including the Hong Kong Observatory, categorised it as a "super typhoon" as it intensified to reach gusts of 227 kilometres per hour.
"The whole of the island should heighten vigilance against severe winds and torrential rains," a spokesman for Taiwan's Central Weather Bureau said.
Almost 3,000 people, most of them tourists, were evacuated Sunday from Taiwan's Green Island and Orchid Island - popular with visitors.
Around 4,000 more were moved Monday ahead of the storm.
New Taipei City Mayor Eric Chu said they were from vulnerable areas, including the hot spring town of Wulai, just outside Taipei.
"In areas that could become isolated during the typhoon, sufficient rescue and communications equipment will be deployed in advance. We hope residents can cooperate with us," said Chu.
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Wulai was hit hard by Typhoon Soudelor in August with some residents unable to return home for weeks.
Aboriginal mountain communities are particularly at risk during typhoons, often hit by flooding and mudslides.
Some are still cleaning up after Soudelor left a trail of destruction.
"A massive amount of rubble caused by the last typhoon is still seen on slopes and river beds. This may cause further damage," the weather bureau said.
More than 24,000 troops are on standby for disaster relief and evacuations, with 100 shelters set up. Emergency response centres have been established in the north and east.
Dujuan was 170 kilometres off the coast of eastern Hualien County at noon Monday.
The storm threatens long-weekend plans for many as Taiwan celebrates the Mid-Autumn Festival.
A concert by US rock band Bon Jovi due to take place in Taipei Monday was cancelled, while 169 international and 59 domestic flights were also pulled.
High-speed rail was due to be suspended mid-afternoon.
Ferry services and flights to outlying islands have already been suspended.
Dujuan will pass near the Japanese island of Ishigaki as it approaches Taiwan.
Japan's meteorological agency has warned it could trigger waves 13 metres high.
The storm is on course to hit mainland China from Tuesday, but is forecast to have weakened by then.
So far there have been no reports of damage or injuries in connection with the typhoon.
Typhoon Soudelor caused at least eight deaths in Taiwan last month as it flooded rivers, ripped up trees, and triggered landslides.
Toppled trees and signboards damaged electricity lines, knocking out power to a record 4.3 million households.
It went on to kill 21 people in China.