April 4 (Bloomberg) -- Taiwan riot police clashed with protesters demanding President Chen Shui-bian's resignation in the worst violence since a disputed March 20 election that Chen won by a quarter of a percentage point.

The opposition has accused Chen of rigging the vote and influencing the outcome by faking an assassination attempt on the eve of the poll. About a thousand protesters, remnants of a larger peaceful rally, gathered on the streets in front of the presidential office and refused police warnings to disperse.

Police in riot gear, backed by water cannons, moved against the crowd with batons and shields after demonstrators broke through barricades and razor wire shortly after midnight in the capital. Protesters hurled metal barricades, stools and rocks as they rushed police. More than a dozen injured were carried away.

``You have made your wishes very clear. The demonstration should stop now,'' Ou Chin-der, Taipei's deputy mayor, said at a briefing after the clash dispersed most of the protesters by 2 a.m. ``Chen should respond,'' he said.

The violence comes as Chen and the opposition Nationalist and People First parties try to work out a deal on a vote recount in an election he won by 30,000 of 13 million votes cast. Taiwan's High Court has given them until Wednesday to decide before it will intervene.

Nationalists

At the earlier rally at nearby Chiang Kai-shek Memorial plaza, Nationalist Party Chairman Lien Chan, 67, who lost to 53- year-old Chen in the election, urged the 40,000 participants to disperse after a couple hours of speeches and songs. The Nationalists disavowed any knowledge of the midnight rally that led to the police clash and resulted in some arrests.

``The demonstrators are very determined. They are even more determined than Lien,'' Huang Yih-jiau, a legislator and spokesman for the People First Party, said before the clash. ``They are very idealistic.''

Several demonstrators included some people dressed in military uniform, including one man in a black navy officer's uniform addressing the crowd with a bull horn.

Taiwan's navy held a briefing, saying its forces are apolitical and neutral and identified the man with the bull horn as a retired officer. The navy plans to sue him, it said.

The opposition parties allege as many as 112,000 service people may have been deprived of the opportunity to vote because of the high alert after Chen's shooting on March 19. The Ministry of Defense put the number at 38,000. The ministry said it would punish any service people in tonight's demonstration.

The Nationalist Party has said it was scaling back rallies after 14 days of demonstrations. The move comes after police in the capital refused to allow more protests beyond yesterday.