Taiwan's High Court ordered ballot boxes to be sealed Sunday after the opposition disputed President Chen Shui-bian's election victory because of a mystery assassination attempt and spoiled ballots.
Protests erupted across the island after Chen's victory by less than 30,000 votes over challenger Lien Chan in Saturday's poll, which took place just hours after the president was shot and slightly injured.
Kuomintang (KMT) leader Lien rejected the result and demanded a recount, saying too many questions remained unanswered over Friday's assassination attempt and the existence of a large quantity of spoiled ballot papers.
Some 30,000 angry KMT supporters faced riot police and water cannons across barbed wire barricades outside the presidential office Sunday in a huge protest called by the party.
Addressing flag waving supporters from the top of a campaign van, Lien, 67, demanded an immediate recount.
"Government agencies should form a taskforce to explain the mysteries related to the trajectory of the bullets and the medical examinations," he said.
Taiwan's premier denounced violence by some KMT supporters in overnight clashes but backed the opposition's right to question the vote after the closest election in the short democratic history of the island off south-east China.
A panel of three judges will hear the opposition case Monday and could order a recount, call more evidence or dismiss the application, Taiwan High Court judge Wen Yao-yuan told AFP. The ballot boxes will be guarded around the clock until the decision is made.
The crisis was triggered when, minutes before Chen's victory was confirmed, a visibly angry Lien demanded answers to questions about the assassination attempt on Chen and Vice President Annette Lu.
Authorities said Chen, 53, and Lu, 59, suffered minor bullet wounds after a mystery attacker fired at least two shots as the pair travelled in an open-top jeep during campaigning in the southern city of Tainan.
Doctors Sunday released pictures of Chen undergoing surgery and police ballistic experts gave a detailed explanation of how the two were injured, but the timing of the shooting has fuelled conspiracy theories about the incident, which analysts said boosted Chen's support.
Chen polled 50.11 percent of the vote compared to 49.89 percent for Lien with more than 13 million votes cast, a turnout of 80 percent.
Premier Yu partly blamed the high number of spoiled ballots on a campaign waged against both candidates by a labour group protesting against smear tactics adopted by both sides. Organiser Lai Hsiang-ling told AFP: "I felt our appeal must have exerted an influence."