LHASA, Tibet — Talks between the Chinese government and envoys of the Dalai Lama have made "no substantial progress,'' and the exiled Tibetan leader threatens China's unity and security, Tibet's Beijing-appointed leader charged Tuesday.

A spokesman for the Tibetan government-in-exile disputed the charges.

The comments provided a rare glimpse into contacts that began in 2002. Both sides have said little publicly about the talks.

Champa Phuntsok, chairman of the official Tibetan government, blamed the Dalai Lama for the lack of success in four rounds of talks. He repeated Chinese accusations that the Tibetan leader wants formal independence for the Himalayan region.

"There has been no substantial progress,'' Phuntsok said in a rare news conference with western reporters in the Tibetan capital.

Thrupten Samphal, a spokesman for the Tibetans' exiled government in the northern Indian town of Dharmsala, responded that the talks have been "fruitful'' and that "there has been a paradigm shift in the attitude of the Chinese.''

In the past, "the Chinese would not listen to Tibetan representatives, (but) now they are very keen to understand and discuss the proposals put forward by the envoys of the Dalai Lama,'' he said.

Privately, Beijing, criticized by western governments for its often harsh 56-year rule over Tibet, has pointed to the contacts as evidence it was trying to heal its split with the Dalai Lama.

The Dalai Lama, who fled into exile in 1959 following a failed uprising against Chinese rule, is still widely revered in Tibet.

Phuntsok is among the highest-ranking ethnic Tibetans in the region's government. But ultimate power in the region lies with its Communist party secretary, a member of China's dominant Han ethnic group.

Phuntsok said the government was trying to change the Dalai Lama's image, telling the public that he is "a political threat and a danger.''

"The Dalai Lama went into exile 40 years ago and since then has clearly been engaged in separatist activities, posing a threat to the unity and security of the nation,'' Phuntsok said.

The Dalai Lama has said he wants only greater autonomy in hopes of preserving Tibet's Buddhist culture.

"When he (the Dalai Lama) says he wants greater autonomy within China, he believes in it. He has made great effort to make his wishes known but China remains suspicious,'' Samphal said.

The talks, the most recent in southern China in February, are believed to have focused on the Dalai Lama's calls for more autonomy and wish to make a bridge-building visit to China.

Many Tibetans say that, in the past five to seven years, the political atmosphere in Tibet has become more repressive. One said in an interview that he was afraid to look up the Dalai Lama on the Internet for fear that he might be spotted by Internet monitors and arrested.

Phuntsok dismissed the Dalai Lama's comments in recent interviews that he wanted to retire in Tibet and would not seek a political or religious role in the country.

"These are only empty words, steps for him to reach independence for Tibet,'' Phuntsok said.

He also criticized the Dalai Lama's proposal for China to expand the official boundaries of Tibet to include areas in neighbouring provinces that were once part of the Tibetan theocracy and still have ethnic Tibetan populations.

"The goal is to press ahead with the independence of Tibet,'' Phuntsok said. "Sources tell us that if this goal is achieved, he will be one step closer to his goal of independence for Tibet.''