More than 100,000 Taiwan opposition supporters have protested, demanding an independent inquiry into an election-eve assassination attempt on President Chen Shui-bian they suspect was staged.
The peaceful rally turned more violent in the evening on Saturday as some protesters tried to storm the presidential office, throwing tables, chairs and bottles at iron barricades and forcing riot police to turn water cannon on them.
"Chen Shui-bian step down! We want the truth! Go democracy!" the demonstrators shouted, waving flags and tooting horns in the third major protest since Chen defeated Nationalist leader Lien Chan in the presidential poll on March 20.
Lien says sympathy votes swung the election and wants an impartial investigation into the mysterious shooting, in which Chen was slightly wounded. The president has rejected the demand so the Nationalists want to hold a referendum on the issue.
"In the last three weeks, Mr Chen Shui-bian has shied away from, avoided and ignored the people's demands. This is not a long-term strategy," Lien told the crowd earlier in the day.
"You cannot forever hide behind the iron barriers and barbed wire," he said to Chen, pointing to the strong barricades that riot police had erected to protect the president's office.
Police estimated about 120,000 people at the rally, double the number at last weekend's event but less than the 500,000 who took to the streets on March 27 in Taiwan's largest protest.
The demonstration was peaceful for most of the day, with the crowd becoming rowdy after Lien left. Last weekend, a few hundred protesters had tried to storm the presidential office and clashed with riot police in the early hours of the morning.
"If we don't put some pressure on him, we won't have a chance to find out the truth," said one elderly man, signing a petition for the referendum to set up a "truth investigation committee."
The cabinet said such a referendum would be unconstitutional as the committee would be endowed with too much power.