Mahathir Halaman, 33, was formally arrested in mid-May by police in his home county of Fuyun, in Xinjiang's Altay prefecture, and handed a one-year jail term by a local court in June.
Sources close to the family, who are residents of Fuyun's Hongtai village, said they had received no formal notification of the legal proceedings against him, nor of the court's verdict.
"He was sentenced to one year's imprisonment because he prayed five times a day, and because he had a younger brother and friends studying overseas in Turkey," a local Kazakh resident told RFA in a recent interview.
Mahathir's brother is currently settled in Kazakhstan.
Mahathir's jailing comes as Xinjiang's government implements a regionwide "localization" policy that seeks to place curbs on ethnic Kazakh Chinese nationals.
The policy targets Chinese nationals who are holders of permanent residence permits, or "green cards," for neighboring Kazakhstan, limiting the length of their stay in the country to six months maximum.
A friend of Mahathir's brother confirmed to RFA that the main reason for his arrest was his habit of praying regularly at home.
After he was sentenced, the local public security office threatened his family, warning them not to speak to anyone about the case.
"This seems to be linked to his worship," the friend said. "The local police originally went looking for his brother, but the brother replied that he is a Kazakhstan citizen, so they detained and sentenced Mahathir instead," he said.
The friend said Mahathir's parents are currently under close surveillance by local police, and aren't allowed to leave the area, while their friends and relatives have also been threatened that they will "bear the consequences" if they "spread rumors" about the case.
Repeated calls to the Fuyun County People's Court rang unanswered on Sept. 9.
New regulations introduced
On July 15, the Xinjiang Autonomous Region Public Security Bureau introduced new regulations, banning Chinese passport-holders with Kazakhstan green cards from staying in Kazakhstan for longer than six months at a time.
The Yili Kazakh Autonomous Prefecture police department has also issued regulations banning retirees from staying in the country for more than one month at a time.
"Offenders will be sent to a 'study center' for re-education," the notice said.
Chinese authorities are 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 last month by Egypt's secret police in an operation activists said was requested by Beijing.
The 200 students, many of them religious students at Cairo's Al-Azhar Islamic University, were detained in a crackdown that began on July 4, and were rounded up in restaurants or at their homes, with others seized at airports as they tried to flee to safer countries, sources told RFA's Uyghur Service at the time.
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.
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