TAIPEI - A top Chinese negotiator shoved to the ground by pro-independence protesters in Taiwan departed the island ahead of schedule Wednesday, potentially complicating delicate talks on improving relations.

Zhang Mingqing, vice president of China's Association for Relations Across the Taiwan Strait, told reporters he was flying back to Beijing for medical tests.

"The police put a lot of manpower to protect my safety and I feel very bad causing them trouble. This should not have happened," Zhang said at Kaohsiung airport in southern Taiwan, where he was heckled by more protesters.

"This violent incident was caused by a few people. It didn't represent the 23 million Taiwanese people."

Television pictures showed more angry scenes at the airport, where police arrested a man who was shouting "Independent Taiwan" among a handful of other protesters.

He was identified by media as a councillor in Kaohsiung for the opposition pro-independence Democratic Progressive Party (DPP).

On Tuesday, Zhang was surrounded by protesters, jostled and pushed to the ground while visiting a temple in the southern city of Tainan.

Zhang has filed assault charges against DPP city councillor Wang Ting-yu, according to an official at Taiwan's Straits Exchange Foundation (SEF).

Wang has insisted Zhang simply tripped.

The episode triggered an angry response from the Chinese government, which demanded Taiwan severely punish the activists who manhandled Zhang.

Zhang's semi-official agency is authorised by Beijing to handle civilian exchanges with Taiwan in the absence of official contacts.

China and Taiwan split in 1949 following a civil war, but Beijing regards the island as part of its territory awaiting reunification.

His trip comes as Taiwan is trying to arrange a new round of cross-Strait negotiations, after talks with China in June led to the first regular direct flights between the island and the mainland in nearly six decades.

Authorities on both sides say the incident should not impact on the second round, which Zhang's boss Chen Yunlin is expected to attend, but some analysts were sceptical.

"China is sending a message with a strongly-worded statement, as well as Zhang's early departure, that it is outraged by the incident," Chang Ya-chung, a political science professor at the National Taiwan University said.

"It will affect what Chen Yunlin brings to the negotiating table if Beijing is not satisfied with Taiwan's handling of the matter."

No itinerary has been finalised for those talks, but local media have said they will be held in Taipei between late October and early November and will focus on cargo flights and shipping links.

Ties have improved dramatically since Taiwan's China-friendly president Ma Ying-jeou took office earlier this year.

He has promised to improve business and tourism ties with China following eight years of strained relations under
Chen.

Reaction in Taiwan to the scuffle was mixed, with the government condemning the incident while the DPP branded Zhang an "enemy" of the island.

"Zhang deliberately came to my hometown Tainan... this is the equivalent of a provocation," former president Chen Shui-bian said Wednesday.

Tainan's city police chief has been demoted to a job in the police highway bureau following the incident, the National Police Agency said.