A U.N. rights committee is calling on China to stop detaining members of the Uighur Muslim minority without cause — and to provide details about how many Uighurs may have been held in detention centers for the past five years.The U.N. Committee on the Elimination of Racial Discrimination said in a report on China's treatment of ethnic and religious minorities that it is alarmed by reports of detentions, mass surveillance, "frequent baseless police stops," and efforts to control Uighurs' movements.The committee cited "reports of detention of large numbers of ethnic Uighurs and other Muslim minorities held incommunicado and often for long periods, without being charged or tried, under the pretext of countering terrorism and religious extremism."While acknowledging that there is no official data on how many people have been detained, the agency noted that estimates commonly range from tens of thousands to more than a million people.The Uighur live in China's far west, in the Xinjiang Uighur Autonomous Region, or XUAR. In recent years, they have faced increased scrutiny and surveillance by the Chinese government — including reports that thousands of people have been held in "political reeducation" centers that allegedly sought to erase their cultural identity.Last week, Chinese officials refused to grant a new visa to journalist Megha Rajagopalan of Buzzfeed, whose work includes an in-depth look at China's development of what she called "a 21st-century police state" in XUAR.China's treatment of the Uighur minority was featured in a hearing on Capitol Hill last month, when the Congressional-Executive Committee on China said the detentions have been called "the largest mass incarceration of an ethnic minority population in the world today."At that hearing, journalist Gulchehra Hoja — a U.S. citizen who grew up in the Uighur Region in China and who works for Radio Free Asia's Uighur language service — told the panel about her family's experience with the detentions: