China has called a mission by the UN rights chief a chance to "clarify misinformation" ahead of her visit on Tuesday to Xinjiang as Uyghurs warned a public relations stunt may lie in wait.
The ruling Communist Party is accused of detaining over one million Uyghurs and other Muslim minorities in the far-western region as part of a years-long crackdown the United States and lawmakers in other Western countries have labelled a "genocide".
China vehemently denies the allegations, calling them the "lie of the century".
Bachelet is expected to visit the Xinjiang cities of Urumqi and Kashgar on Tuesday and Wednesday as part of a six-day tour.
She met Foreign Minister Wang Yi ahead of her journey to Xinjiang, who also "expressed the hope that this trip would help enhance understanding and cooperation", according to a readout of the meeting released late Monday.
But Uyghurs, the main victims of an alleged campaign of repression, raised doubts about her presence if her trip is as highly-controlled as expected.
Nursimangul Abdureshid, a Uyghur living in Turkey, said she was "not very hopeful that her trip can bring any change".
"I request them to visit victims like my family members, not the pre-prepared scenes by the Chinese government," she told AFP.
"If the UN team cannot have unlimited access in Xinjiang, I will not accept their so-called reports."
Another Uyghur, Jevlan Shirememet, called on Bachelet to help him contact his mother who he has not seen for four years.
The Turkey-based 31-year-old -- from the province's northern reaches near the border with Kazakhstan -- also said he hoped Bachelet would venture further than her itinerary.
"I don't know why she can't visit these places," he told AFP.
- 'Unfettered access' -
Regional capital Urumqi -- population four million -- houses major government bodies believed to have orchestrated the province-wide campaign China described as a crackdown on religious extremism.
It is home to a sizeable Uyghur community and was the site of deadly ethnic clashes in 2009 as well as two terrorist attacks in 2014.
Meanwhile, Kashgar -- home to 700,000 people -- lies in the Uyghur heartland of southern Xinjiang.
An ancient Silk Road city, it has been a major target of Beijing's crackdown, researchers and activists say, with authorities accused of smothering the cultural hub in a high-tech security blanket while bulldozing Uyghur homes and religious sites.
The outskirts of both cities are pockmarked with what are believed to be detention camps, part of a sprawling network of recently built facilities stretching across the remote province.
Campaigners have voiced concern that Chinese authorities will prevent Bachelet from conducting a thorough probe into alleged rights abuses and instead give her a stage-managed tour with limited access.
The US has said it is "deeply concerned" that she had not secured guarantees on what she will see, adding that she was unlikely to get an "unmanipulated" picture of China's rights situation.
Bachelet also gave assurances on her access to detention centers and rights defenders during a Monday virtual meeting with the heads of dozens of diplomatic missions in China, according to diplomatic sources in Beijing.
Caroline Wilson, the UK's Ambassador to China, was on the call and said she stressed "the importance of unfettered access to Xinjiang and private conversations with its people".
"There is no excuse for preventing UN representatives from completing their investigations," Wilson wrote on Twitter.
Bachelet's office has also said she will meet with civil society organizations, business representatives and academics.
In addition to mass detentions, Chinese authorities have waged a campaign of forced labor, coerced sterilization and the destruction of Uyghur cultural heritage in Xinjiang, researchers and campaigners say.
Uyghurs overseas have staged rallies in recent weeks pressing Bachelet to visit relatives believed to be detained in Xinjiang.