Turkey told Beijing on Tuesday it was worried over reports Uighur people had been banned from worship and fasting during the holy month of Ramadan in China's far western region of Xinjiang, the foreign ministry said.
Earlier this month, some local governments in Xinjiang stepped up controls on the Islamic faith followed by the Turkic Uighur people ahead of Ramadan, including restrictions on fasting.
"Our people have been saddened over the news that Uighur Turks have been banned from fasting or carrying out other religious duties in the Xinjiang region," Turkey's foreign ministry said in a statement.
"Our deep concern over these reports have been conveyed to China's ambassador in Ankara."
The holy month of Ramadan is a sensitive time in Xinjiang following a rise in attacks blamed by Beijing on Islamist militants over the past three years in which hundreds have died.
Earlier in June, state media and government websites in Xinjiang published stories and official notices demanding that party members, civil servants, students and teachers in particular do not to observe Ramadan, something that also happened last year.
Muslims worldwide observe Ramadan, when many abstain from eating and drinking during daylight hours.
China's Communist Party says it protects freedom of religion, but it maintains a tight grip on religious activities and allows only officially recognised religious institutions to operate.
China has around 20 million Muslims spread throughout the country, only a portion of which are Uighur, a Turkic-language speaking group that calls Xinjiang home.