There is no accurate figure of the number of ethnic Uighurs who have gone to fight with militant groups in Syria, China’s special envoy for the Syrian issue said on Monday, adding he hoped to return to Syria to gain a clearer picture. China is worried that Uighurs, a mostly Muslim people who speak a Turkic language and hail from China’s far western region of Xinjiang, have gone to Syria and Iraq to fight for militants, having traveled illegally via Southeast Asia and Turkey. The Syrian ambassador to China, Imad Moustapha, told Reuters last year that up to 5,000 Uighurs are fighting in various militant groups in Syria. ISIS claimed responsibility for the killing of a Chinese hostage in 2015, highlighting China’s concern about Uighurs it says are fighting in the Middle East and fears they may return to China to carry out attacks. Xie Xiaoyan told a news briefing in Beijing that China talks with all countries, including Syria, about the fight against terror. “As for how many Uighur terrorists there are, I’ve seen all sorts of figures. Some say 1,000 or 2,000; 2,000 or 3,000; 4,000 or 5,000, and some say even more,” Xie said. “I hope that next time I have the opportunity to go to Idlib to have a look,” he added, referring to the last big swathe of territory still held by Syrian rebels. Idlib is still controlled by an array of insurgent groups, mainly dominated by extremists, according to Reuters. China has blamed a group called the East Turkestan Islamic Movement, or ETIM, for many of the attacks in recent years in Xinjiang, though some experts have questioned whether the group exists in any coherent form. Xie cited a United Nations report that there were 20,000 or 30,000 people fighting with terror groups in Syria and Iraq. “Certainly in those areas there are rather a concentration of ETIM terrorists. This is certain,” he added.