Pro-independence protesters in Taiwan have attacked a visiting official from China, in an incident which was quickly condemned by Beijing.
Zhang Mingqing, was pushed to the ground in the scuffle, and a protester jumped on the roof of his vehicle.
Mr Zhang is from a mainland body responsible for relations with Taiwan, which Beijing regards as a breakaway province.
The protesters were calling for full independence for the island.
The attack on Mr Zhang was shown on television news broadcasts across Taiwan, and correspondents say the images are likely to inflame tensions between the pro-independence and pro-Beijing camps.
China has claimed sovereignty over Taiwan since the end of the Chinese civil war in 1949 and insists it must be reunited with the mainland, by force if necessary.
China-Taiwan relations had been improving under the administration of new Taiwanese President Ma Ying-jeou, who is keener than his predecessor Chen Shui-bian on close ties with Beijing.
But Beijing has already reacted angrily to Tuesday's attack, writing to the Taiwanese authorities to express its "strong indignation and severe condemnation" of the incident, according to the state news agency Xinhua.
"The presidential office expresses regrets over the incident and condemns the violence stirred up by a small number of people," Wang Yu-chi, a spokesman for Mr Ma, told the Associated Press.
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