Present Chen Shui-bian, in closely watched inaugural address, pledged Thursday to avoid any steps during his next four-year term that would alter the status quo in Taiwan's tense relationship with mainland China.

Chen, 53, was sworn in under a relentless downpour in a ceremony attended by representatives of the 26 nations that still maintain diplomatic relations with the Republic of China, as this self-governed island is formally known.

Chen, in his hour-long address, nevertheless vowed to press forward with his program to give Taiwan "a new version of the constitution."

The Chinese government in Beijing has depicted Chen's constitutional reform plans as steps designed to move this island and its 23 million inhabitants toward independence from the mainland, something the Communist government has vowed to prevent, by force if necessary.

Chen said his constitutional changes would be designed only to improve the efficiency of Taiwan's government and would not touch on the issues of sovereignty, territory or Taiwan's political status, that Beijing has defined as red lines not to be crossed under threat of war.

Chen's renunciation of steps leading toward formal independence for Taiwan appeared to respond to pressure from the United States and other nations that he refrain from exacerbating his tense relationship with the mainland, which has deployed about 500 short-range missiles on the other side of the 100-mile Taiwan Strait.

He called on Beijing to reciprocate by moving with him to renew contacts and diplomatic dialogue, adding that threats of force, such as the one issued in a Chinese statement on Monday, would only impede the process.

"This will only serve to drive the people of Taiwan farther away and widen the gap across the Taiwan Strait," he said.

Chen reaffirmed the commitments he made in his inaugural address four years ago not to take any initiatives that would alter Taiwan's status and move it formally toward independence, that Chen's comments have led many to believe are his ultimate goal.

"Those commitments have not changed, nor will they change over the next four years," he said.

At the same time, Chen emphasized that in the 55 years since nationalist Chinese fled to Taiwan and set up the Republic of Taiwan, this island has developed along a separate path from the Communist mainland. In particular, he said, in recent years, Taiwan has developed a vibrant democracy with direct presidential elections and a political tradition that separates Taiwanese from their mainland cousins.

"This is a fact," he declared. "History has given rise to the development of two very different political systems as well as two dissimilar ways of life on either side of the Taiwan Strait."

As the inauguration ceremony began, hundreds of opposition supporters gathered for a protest at a park in the eastern part of the capital, Taipei.

Chen was reelected March 20 after campaigning on a China-bashing platform and claiming that he could best protect Taiwan from China's plans to swallow up the tiny island.

This week, China issued a new series of warnings that Taiwan would trigger a war if it rejected eventual unification.

China "will never tolerate Taiwan independence," the Communist Party newspaper People's Daily and other state media said in a series of bellicose commentaries Wednesday. They warned that China was ready to use "non-peaceful means" to keep Chen from trying to make the self-ruled island's de facto independence permanent.

A day before the inauguration, the China Daily newspaper wrote that China wants Chen to soften his "radical separatist stance in his inauguration speech," that China would view as a blueprint for Chen's second term.

In a statement Monday, China vowed to "firmly and thoroughly" crush any moves toward independence, but urged Chen to resume talks on unification. The statement for the first time called for "mutual trust in the military field" but did not elaborate.

President Chen Shui-bian is sworn in for a second four-year term at the Presidential Palace in Taipei.