Taiwan has started using unmanned surveillance aircraft to spy on China to reduce the risk to its pilots from an increased deployment of Chinese missiles, media reported Sunday.

The army in March commissioned a fleet of 32 unmanned aerial vehicles, or drones, developed by the military-run Chung Shan Institute of Science and Technology.

A Taiwanese rights activist and outspoken critic of his government's attempts to seek closer ties with Beijing criticized Chinese authorities after he was denied entry to Hong Kong Sunday.

Chen Wei-ting, a key figure in an unprecedented student-led protest occupation of Taiwan's parliament earlier this year, had planned to attend a mass rally Tuesday in Hong Kong in support of greater democracy there.

Taiwan's main opposition party on Wednesday dropped out of the mayoral race in the capital Taipei, seen as a major barometer for the presidential elections.

The Democratic Progressive Party (DPP) said it would not be nominating a candidate for the Taipei mayor in order to back the campaign of popular political novice Ko Wen-je, so that the opposition camp could present a united front in the race.

Vietnam on Tuesday accused a Chinese ship of ramming and sinking one of its fishing boats, fanning territorial tensions over Beijing's deployment of an oil rig in contested waters.

The incident, which China's rival Japan described as "extremely dangerous", comes during an ongoing tense confrontation between the communist neighbours in the South China Sea that has triggered international alarm.

Taiwanese police arrested 19 people for threatening copycat attacks following a stabbing spree aboard a Taipei subway train, an unprecedented attack which sparked panic among commuters, officials said Monday.

Cheng Chieh, a 21-year-old knife-wielding attacker, killed four people and wounded nearly two dozen others last Wednesday in the first fatal attack on the city's subway system since it began operations in 1996.

Several hundred Filipino and Vietnamese protesters united in a march in the Philippine capital on Friday, demanding that China stop oil drilling in disputed South China Sea waters.

Filipino riot police blocked the entrance to a high-rise building that houses the Chinese consulate in Manila's financial district as around 200 protesters marched on the office.

China's President Xi Jinping met longtime Taiwanese politician James Soong in Beijing on Wednesday, state media said, the latest step in incrementally improving ties in recent years.

China's official news agency Xinhua described Xi as the general secretary of the Communist Party of China Central Committee, and Soong as chairman of Taiwan's People First Party, suggesting that the two met in their party rather than official capacities.

A Taiwan air force major was jailed for 20 years Monday for leaking military secrets to China in the latest espionage case to hit the island.

Hau Chih-hsiung, who had served at an air base in the southern county of Pingtung, was charged last month with passing to China confidential information related to the E-2K, an improved version of the Grumman Hawkeye early warning aircraft.

Taiwan this month mobilized hundreds of marines for its largest military exercise since 2000 near disputed islands in the South China Sea, a legislator said Monday.

Lin Yu-fang said the landing drill was held on the Taiwan-administered island of Taiping, part of the Spratlys -- a chain which is also claimed in whole or in part by China, Vietnam, Malaysia, the Philippines and Brunei.

Taiwan police on Monday used water cannon to dislodge hundreds of overnight sit-in demonstrators, demanding the scrapping of a nearly completed nuclear power plant, one of the most controversial issues to have gripped the island for 30 years.

Tens of thousands of anti-nuclear demonstrators blockaded one of the busiest streets in the capital Sunday, forcing the ruling Kuomintang party to yield and halt construction work at the plant.