A US human rights diplomat headed to China's mainly Muslim region of Xinjiang on Wednesday for talks with religious and political leaders.
Human rights groups have documented widespread human rights abuses in the region, and Chinese crackdowns in Xinjiang have been condemned overseas.
The US diplomat, Lorne Craner, is hoping to dispel criticism from human rights groups that the US is using the ethnic-Uighur population as a bargaining chip in its war against terrorism.
The visit follows talks in Beijing at which China agreed to invite three United Nations human rights experts to visit China, Mr Craner said.
"The Chinese agreed to invite the UN rapporteur on torture, the rapporteur on arbitrary detention and the rapporteur on religious freedom," said Mr Craner, US assistant secretary of state for democracy and human rights.
"These are unconditional invitations," which would be effective immediately."
China has not formally commented on the invitations, but Chinese foreign ministry spokesman Liu Jianchao said the two days of talks had been "constructive and fruitful".
Correspondents say the unconditional invitations are seen as a significant step, because although the rapporteur on torture had previously been invited, Beijing had attached restrictions.
China's Muslim minority
Mr Craner will now spend two days in Xinjiang, where separatists have been waging a 20-year-old campaign to establish an independent state called East Turkestan.
Earlier this year the US Government listed one Xinjiang independence group as a terrorist group, a move human rights groups feared China would use to justify crackdowns on dissent.
Human rights groups say the US is turning a blind eye to China's abuses in Xinjiang in return for China's support in its war on terror.
But Mr Craner said the decision to ban the little-known East Turkestan Islamic Movement (ETIM) was not a justification for China to suppress human rights.
"It is our understanding that our decision on ETIM is being presented by some Chinese officials as a licence - that the US has bought into the notion that Uighurs are terrorists," he told Reuters news agency.
"We want to dispel that notion."
Human rights groups have appealed to the US delegation to press for the release of dissidents, as news emerged that the publisher of a pro-democracy website has been detained.
Li Yibin was secretly detained about a month ago in Beijing, according to New York-based Human Rights in China.
Mr Li, believed to be 28, published the online journal Democracy and Freedom. He was detained around the same time as a female Beijing college student, Liu Di, who was detained on 7 November, the group said.
Amnesty International last month said the authorities had detained at least 33 people in a crackdown on internet dissidents.