An estimated 5,000 members of China’s Uighur, or Uyghur, minority group are waging jihad on behalf of the Islamic State (ISIS/ISIL), al-Qaeda, and other terrorist groups, according to Reuters, citing the Syrian ambassador to Beijing.

“Our estimated numbers, because of the numbers we fight against, we kill, we capture, we wound, would be around 4-5,000 Xinjiang jihadists,” Ambassador Imad Moustapha said. “China as well as every other country should be extremely concerned.”

This year, both ISIS and its rival al-Qaeda released videos threatening to attack China. Both groups featured Uighur fighters within their ranks.

Now Reuters reports: “Up to 5,000 ethnic Uighurs from China’s violence-prone far western region of Xinjiang are fighting in various militant groups in Syria, the Syrian ambassador to China said on Monday, adding that Beijing should be extremely concerned about it.”

Moustapha added that most Uighurs named were “fighting under their own banner to promote their separatist cause,” Reuters reported on May 8.

The spokesperson for the Germany-based World Uyghur Congress, Dilixiati Rexiti, reportedly claims that the 5,000 estimate for Uyghur jihadists is overblown to garner more weapons and economic aid from China.

In backing the spokesperson’s assertions, U.S.-based China rights advocate Liu Qing indicated it “was very unlikely that such a high number of Uighur people could have left China as Beijing imposes strict controls on the movements of the Uighur population.”

“The proportion of Uighur fighters to their total population is also too high,” Liu told Radio Free Asia (RFA).

Chinese state media has claimed that as many as 300 Uighurs have traveled to join ISIS and other jihadist groups overseas.

An increasing number of Uighur (or Uyghur) jihadists are leaving their homeland China to join Islamic extremist groups in the Middle East.

Meanwhile, RFA reports:

Uyghur students enrolled in schools outside China are being ordered by Chinese authorities to return to their hometowns by May 20, with family members in some cases held hostage to force their return, sources in Xinjiang and in Egypt say. Launched at the end of January by authorities across the Xinjiang region, the campaign has frightened targeted students, some of whom have disappeared or been jailed after coming back, a Uyghur studying at Egypt’s Al-Azhar University told RFA’s Uyghur Service.

China has repeatedly been accused of oppressing and persecuting the Uighur Muslim minority. Beijing denies the allegations.