Chinese authorities in the northwestern region of Xinjiang are continuing their wave of arrests of ethnic minority Kazakhs and Uyghurs, sources in the regional told RFA on Wednesday.



A Kazakh source close to the police department in Xinjiang's regional capital, Urumqi, said police are now being issued with quotas for the detention of the mostly Muslim Uyghurs and ethnic Kazakhs.



Police are targeting anyone who expresses a critical opinion of the ruling Chinese Communist Party on social media, as well as those with overseas links, such as family who live or study abroad, sources said.



Many of those detained are being sent to re-education centers across the region, while some face criminal prosecution, they said.



"They have to detain 3,000 Kazakhs or Uyghurs per week," the Kazakh source close to the Urumqi police department said.



A second Kazakh source gave the example of Urumqi sole trader Adilbek Hasmubai, who was reported to police after he sent his computer to a repair shop and the shop assistant viewed photos and images of a Kazakhstan lawmaker stored on the hard drive, and reported him to police.



Adilbek, 32, was taken away by police in Urumqi, and several of his friends and associates were later also detained, after his computer was found to contain images of them posing in photographs with Kazakhstan Mazhilis member Bekbolat Tleukhan, who has spoken out about China's treatment of Kazakhs.



More than 20 people were detained in connection with the case in Ili Kazakh Autonomous Prefecture and Tacheng city, including Aigul Musakhan, 28, Tumarbek Sadek, 32, and Tohtar Bisanbey, 32.



An employee who answered the phone at the Tianshan district police department in Urumqi on Wednesday hung up immediately when contacted by RFA.



The source said the number of detainees implicated in the Adilbek case alone would likely continue to expand.



More cells being built



A Kazakh source living in the north of Xinjiang said the recent waves of detentions has outstripped existing capacity, prompting the authorities to build more detention facilities, including those with cells just one meter high.



"[new construction] has already started happening in the jails near where I live," the Kazakh source said. "I heard that there are two reasons for this: one is that the [existing jails] are packed with people, and the other is that they are making a distinction between political prisoners and ordinary criminals."



"The ceilings are just one meter high, so a person can't stand upright: they have to squat down."



A second source in the same area said authorities are continuing to confiscate the passports of Kazakhs in the region, in a policy that has long been used to restrict Uyghurs' freedom of movement.



"They don't want them going to visit relatives in Kazakhstan," the source said. "They are planning to tell the United Nations Human Rights Council about this situation, to try to get their support."



He said relatives who are citizens of Kazakhstan are also finding it hard to get Chinese visas to visit relatives in Xinjiang.



Targeted for ties abroad



Chinese authorities began detaining ethnic minority Kazakhs several months ago, sending them to police-run detention centers or re-education camps across the region.



Those being targeted often have overseas links, including a history of overseas study or family and friends across the border in Kazakhstan.



Chinese authorities are also believed to be holding a number of ethnic minority Kazakhs for wearing "Islamic" clothing and praying, a practice forbidden by the ruling Chinese Communist Party on university campuses across the country.



Dozens of Kazakhs have also faced detention, intimidation, and the confiscation of their passports and other documents because they have family members living or studying overseas.



Ethnic minority Kazakh Muslims were among some 200 ethnic minority holders of Chinese passports targeted in August by Egypt's secret police in an operation activists said was requested by Beijing.



Official figures show that there are around 1.5 million Kazakhs in China, mostly concentrated in and around the Ili Kazakh Autonomous Prefecture.



China has previously welcomed Kazakhs who wished to relocate from Kazakhstan, but many Kazakhs with Chinese nationality are now heading back in the other direction, with their numbers peaking at nearly 38,000 in 2006.



Reported by Qiao Long for RFA's Mandarin Service. Translated and edited by Luisetta Mudie.