BEIJING, OCT. 27 -- A leading Chinese official today declared a commitment to protect the rights of China's often beleaguered scientists and other intellectuals and improve their working and living conditions.

Song Jian, minister of the state science and technology commission, said astrophysicist Fang Lizhi, China's best known dissident, is free to do research and travel abroad. But he said Fang, sometimes described as China's Andrei Sakharov, the Soviet scientist and political dissident, is unqualified to comment on politics.

Song, a member of the Communist Party Central Committee and a fellow scientist, attempted to reassure Chinese scientists and other intellectuals that the party will not persecute them as it has numerous times in the past.

But the official, speaking at a news conference, stopped short of saying the party would tolerate a diversity of political views, as Fang Lizhi has proposed.

Intellectuals in China often are paid less than manual laborers and their living conditions are at times far worse.

One of the party's main aims in recent years has been to recruit more intellectuals for the country's economic and technological modernization. For decades, the party has relied heavily on peasant recruits for its members.

A number of intellectuals, such as Fang and university students who consider him a hero, have demanded western-style political freedoms. Fang was expelled from the Communist Party earlier this year, but the action seemed to enhance his prestige among some intellectuals.

Song met with reporters on the third day of a major party congress, the first in five years. Its aim is to endorse policies and leadership changes that will affect China's course through the end of this century.

According to recently released official figures, over the last five years the party has recruited more than 1.2 million new members who are professionals or intellectuals. But more than 18 million of the party's 46 million members are peasants, an official spokesman said.

"The Central Committee . . . will take more measures to further improve the living and working conditions of intellectuals," said Song, who was in charge of designing China's first generation of land-to-air missiles in the 1950s.

Song was asked by a reporter from Taiwan who unexpectedly appeared at today's news conference whether China would formulate laws to protect intellectuals in view of the widespread persecution of intellectuals during the Cultural Revolution of 1966 to 1976.

Song answered that he personally had suffered during the Cultural Revolution and was sure that what had happened then would not recur.

"My colleagues and myself all deem that protecting the rights and interests of the scientists and improving the living and working conditions for the scientists and technicians is one of the important and glorious duties," Song said.

The Taiwan reporter, Pi Jiexing, 32, momentarily disrupted the press conference when he entered the Great Hall of the People. As a representative of the Trans-World News Agency, he is the fourth reporter this year to defy a Taiwan government ban on reporters from Taiwan traveling to the mainland.

Song was asked why the outspoken Fang had not been allowed to travel to England after attending an academic conference in Rome this summer. Fang had been invited to attend the 300th anniversary celebration of the publication of Newton's theory of gravity in Cambridge. At the time, Fang said authorities gave no reason for their decison to deny him permission to attend.

Song said he was unaware of the decision. He said no restrictions had been imposed on Fang by the science and technology commission, but added that restrictions on travel funds, which affect all Chinese scientists, might have been the reason.

Song described Fang as an accomplished astrophysicist and said the government would assist him in his work regardless of his party membership.

But in response to a questioner who quoted Fang as saying that scientific study leads to a rejection of Marxism, Song said, "I don't think Fang is a social scientist, much less a Marxist."

Fang recently agreed to be interviewed by a Washington Post reporter, but said he first had to obtain approval from his work unit. An official in Fang's work unit said Fang was too busy.

Meanwhile, in what appears to be a move to ease pressure on scientists, the party has decided that party secretaries in scientific institutes will be elected, and will serve only on a part-time basis, Song said.

The official New China News Agency said that members of the party Central Committee and members of a discipline inspection commission will, for the first time, be selected through preliminary elections with more candidates running than there are seats. It appeared, however, that the party will choose all of the candidates in advance, making this more a cosmetic gesture than a substantive change.