Michelle Bachelet begins her China visit on Monday, the first such trip for the United Nations High Commissioner for Human Rights to the country since 2005.
The six-day trip will see Bachelet visit the Xinjiang region. Beijing has repeatedly denied any mistreatment of Uyghurs there, adding her visit should not be based on the presumption of guilt.
The High Commissioner's office said last year it believes the mostly Muslim ethnic Uyghurs have been unlawfully detained, mistreated and forced to work.
Her office had earlier said that "the purpose of her visit is really focusing on a dialogue with the Chinese authorities on a range of domestic, regional and global human rights issues".
China had denied the existence of any detention camps, saying it had set up vocational training centres with dormitories where people can check themselves in to learn about law, Chinese language and vocational skills.
The central authorities said such centres are necessary to curb the "Three Forces" of terrorism, separatism and religious radicalism in the region. Xinjiang Governor Shohrat Zakir said in 2019 all trainees had "graduated".
Beijing has denied Western allegations of forced labour, genocide and human rights abuses and repeatedly warned other countries not to interfere in its domestic affairs. (Reuters)