BEIJING, July 28 (Reuters) - Doksuri regained super typhoon strength on Thursday (Jul 27) in its final approach to south-eastern China after pummelling Taiwan and the northern Philippines with rain and strong winds that led to the capsize of a ferry in which at least 25 people died.

As of 5pm Beijing time, the winds around the eye of the storm had reached up to 187kmh, putting Doksuri back on the top rung of China's tropical storm categorisation system after weakening earlier.

The ferry sank near the Philippine capital of Manila after passengers alarmed by strong winds rushed to one side of the boat, overturning it. As many as 36 people have been killed this week during Doksuri's transit off the northern Philippines.

Businesses and schools were shut in southern counties of Taiwan amid warnings of landslides and floods. All domestic flights and ferry lines were suspended, while more than 100 international flights were cancelled or delayed. Railway services between southern and eastern Taiwan were halted.

More than 5,700 people were evacuated as a precaution, mostly in the mountainous southern and eastern Taiwan, where more than 0.7m of rainfall was recorded in some areas.

The storm cut power to more than 49,000 households across Taiwan, although supply has since been restored to most.

"Typhoon Doksuri should not be underestimated," Chen Chi-mai, mayor of the southern port city of Kaohsiung, said on Facebook late on Wednesday.

Taiwan's armed forces pressed ahead with a large-scale anti-landing drill on a beach near Taipei Port just outside the capital, simulating the repulsion of an enemy force with ground troops and tanks amid high military tensions with neighbouring China.

The storm has disrupted parts of Taiwan's main annual Han Kuang exercises and air-raid drills that started on Monday. Authorities cancelled some exercises citing safety concerns and the need to make preparations for the typhoon.

Doksuri is expected to make landfall in China on Friday morning somewhere between Dongshan and Putian in the southeastern province of Fujian.

On Thursday, three coastal cities in Fujian shut schools, businesses and factories, while flood control authorities in one of them, Xiamen, warned of a "serious impact".

The China Meteorological Administration forecast that Doksuri would be weaker than 2016's Typhoon Meranti, the strongest storm to hit China's coast since 1949 which killed at least 11 people.

Beijing launched emergency flood control operations in the country's southwest on Wednesday night after torrential rains in the provinces of Sichuan, Guizhou and Yunnan as well as the nearby metropolis of Chongqing.

Heavy flooding in the city of Luzhou, Sichuan province, swept cars on to tree trunks, according to videos circulating on Chinese social media.

Passenger ships and fishing boats have also been grounded in parts of coastal Zhejiang province immediately north of Fujian.