China has detained an estimated one million Uighur Muslims in concentration camps, where they are undergoing re-education programmes allegedly intended to combat extremism.

The Uighur are an ethnic Turkic group that practices Islam and lives in Western China and parts of Central Asia.

Beijing has accused the minority in its Western Xinjiang region of supporting terrorism and implemented a surveillance regime.

Uighur groups had appealed to Saudi’s powerful young prince to take up their cause, as the ultraconservative kingdom has traditionally been a defender of the rights of Muslims worldwide.

But Muslim leaders have so far not broached the issue with China, which has in recent years become an important trading partner with the Middle East.

Hami Aksoy, a spokesperson for Turkey's Foreign Office, however described China's treatment of its Uighur population as "a great cause of shame for humanity" last month and asked it to close the "concentration camps".

President Recep Tayyip Erdogan had once accused China of "genocide" but has since established closer diplomatic and economic relations with Beijing.

Imran Khan, prime minister of Pakistan, where Prince Salman has just visited, said he “did not know” much about the conditions of the Uighurs.