TAIPEI, Taiwan, Dec. 1 -- A political party that favors Taiwan's independence won the largest number of seats in the legislature for the first time when millions of voters cast ballots today for allies of President Chen Shui-bian, despite an ailing economy and China's efforts to discredit him.

The strong showing by Chen's Democratic Progressive Party is certain to alarm China's Communist government, which claims this self-governing island of 23 million people as its own and threatens to seize it by force if necessary.

Chen has promised not to provoke China by declaring independence. But his party's growing strength suggests that people in Taiwan continue to resist reunification despite Beijing's alternating efforts to intimidate them with threats of war and to entice them with investment opportunities.

Official results released tonight showed that Chen's party won 87 of the 225 seats in the legislature and 37 percent of the vote, sweeping aside the Nationalist Party that governed Taiwan for nearly five decades and supports eventual reunification with China.

"We have officially become the largest party in the legislature," declared DPP chairman Frank Hsieh at a victory celebration. "This is a triumph for the public in general, because Taiwan has taken a big step toward becoming a mature democracy."

The Nationalists, who lost the presidency to Chen last year in the island's first democratic transition of power, won only 68 seats in the legislature and 31 percent of the vote, down from the 110 seats they held previously. It was a stunning loss for the party that Chiang Kai-shek led to Taiwan in 1949 after losing the civil war to the Communists in China.

"We did not win," conceded Nationalist leader Lien Chan. "But we are still the largest opposition party. We will step up negotiations with others so we can together help stabilize politics."

The results also represent a serious defeat for China, which had sought to undermine Chen by ignoring his government and wooing his political opponents and Taiwanese businesses. Officials in Beijing had hoped the island's economic problems -- Taiwan is suffering its worst recession on record -- and an exodus of Taiwanese companies to China would weaken Chen.

But Chen emerged from today's election with his strongest political mandate yet. Voters chose not to blame him entirely for Taiwan's problems, and instead punished the Nationalists for repeatedly thwarting his legislative agenda.

Another winner was the People First Party, a pro-unification organization led by former Nationalist James Soong, which more than doubled its seats in the legislature from 20 to 46.

Although Chen failed to win a legislative majority, he is expected to form an alliance with the fledgling Taiwan Solidarity Union, a party founded by former president Lee Teng-hui that is even more strongly in favor of Taiwan's independence than the DPP. With its support, Chen would need to persuade only about a dozen other legislators to join him to form a coalition.

"President Chen comes out of this election in a very good position," said Emile Sheng, a political scientist at Taipei's Soochow University. "There are a lot of options available to him. In effect, he already controls enough seats, so there's no way the Nationalists can block major legislation."

In a brief statement tonight, Chen reached out to the opposition parties. "Regardless of the election outcome, the end of agitation should be the beginning of reason. The end of the elections should mark the beginning of cooperation," he said.

While the DPP supports independence, Chen has moved the party away from that position, relaxing limits on Taiwanese investment in China, easing restrictions on Chinese tourists and reporters in Taiwan, and repeatedly offering to open talks with Chinese President Jiang Zemin.

But Beijing remains suspicious of Chen because he refuses to agree in advance that Taiwan is part of China, the "one China" principle.

The Chinese government issued no immediate reaction to the election results. State-run media issued a one-sentence report late tonight listing the number of seats won by each party without any commentary.

China has shown signs of growing impatient with Chen. During the campaign, Chen said accepting the "one China" principle would destroy Taiwan. He appeared to reject a Nationalist-supported plan to reopen talks by agreeing there is "one China" but noting that the two sides disagree on what that term means.

Later, Chen's aides sought to clarify his position, saying he was willing to discuss anything with China without preconditions. But in unusually frank remarks, Chinese Foreign Minister Tang Jiaxuan dismissed Chen as a liar: "I hold him in contempt. His mouth cannot speak the truth, and everything he says is a lie."

Some analysts say Beijing might be willing to meet with Chen now that he has consolidated his political position, and it appears unlikely he will be lose power anytime soon. But others say that with a critical Communist Party leadership transition scheduled next year, Chinese officials will be reluctant to appear weak on Taiwan by compromising with Chen.