Beginning a historic 12-day fact-finding mission, the United Nation's chief torture investigator "praised" China's leaders for acknowledging the widespread abuse of prisoners in the nation's jails.

Arriving to China on Monday, Manfred Nowak, UN Human Rights Commission's special rapporteur on torture said Beijing has offered him freer access to prisoners than the United States was prepared to give him on a recently cancelled trip to Guantanamo Bay, after he received government assurances it would cooperate with him and allow him unannounced visits to prisons and private talks with detainees, according to AP.

"I'm very grateful to the Chinese government that they did invite me and also that they accepted my terms of reference," he said on an interview with BBC aired on Tuesday.

"There is a growing awareness that torture is quite widely practiced in the common criminal proceedings (in China) by the police and that something needs to be done," he said on the BBC. "I see my visit also as part of this growing awareness."

Nowak further commented on the first meeting on Monday with the officials from the ministry of foreign affairs and justice as "very good."

Standing unwavered in his duty, Nowak did not take this visit to China's jails know for widespread human rights abuses lightly.

"China is huge country and it has of course a long tradition of torture and ill treatment and you can't change that from one day to the other, so it is a policy of taking small steps," Nowak said.

"People have been sentenced to death and afterwards it turned out that the 'victims' actually were alive, so it was clear that the only reason why they have been sentenced to death and executed was that their confession had been extracted by torture."

Aside from visiting prisons in Beijing, Nowak will visit the Tibetan capital of Lhasa, before going onto Urumqi and Yining in the Uighur Muslim-populated Xinjiang region.

Police in both regions have engaged in long-standing crackdowns on separatism, and human rights groups regularly report widespread abuse of detainees there.

Nowak's visit is the result of years of negotiation between the UN and China on allowing unfettered access to prisons, private talks with detainees and no retaliation on prisoners.

In the early 1990s, a UN special rapporteur on arbitrary detention visited prisons in Tibet. But prisoners were punished for what they told the investigator, right group say.

"They were given longer sentences and some were even beaten," Nicholas Becquelin, Hong Kong director for Human Rights in China, told AFP.

"The UN does not want to see this happen again, so that is why it has taken so long to get this visit again."

Nowak said that the terms of reference for his visit to China were better than what the United States had offered on a proposed visit to Guantanamo Bay in Cuba, where prisoners from the wars in Iraq and Afghanistan are being held.

"It was made clear by the Pentagon that they would not be willing to accept my terms of reference, so there was no other option than to finally cancel the mission," Nowak said.

Nowak last week cancelled his scheduled December 6 visit to Guantanamo Bay after failing to win assurances from the United States that he would be able to meet detainees privately.

The Special Rapporteur will submit a comprehensive written report on the visit to the Commission on Human Rights at its sixty-second session in 2006.