We must fully recognise that Xinjiang faces a very serious situation in maintaining long-term social stability, and we must make a serious crackdown on violent terror activities the focal point of our struggle Yu Zhengsheng, China's fourth-ranked Communist Party leader At least 50 people died in September in an attack on a Chinese coal mine in the far-western region of Xinjiang, Radio Free Asia reported on Thursday. The news came after a visiting senior mainland leader warned that the security situation in the violence-prone region was “very serious”. The United States-based Radio Free Asia said the number of people killed in the September 18 attack at the Sogan colliery in Aksu had reached 50, with most casualties among members of the Han Chinese majority. Police have blamed the attack on knife-wielding separatists. The attack was reported as the country marked 60 years since the establishment of what it calls the Xinjiang Autonomous Region, complete with images on state television of happy ethnic minorities dressed in colourful outfits dancing in celebration. On Wednesday Yu Zhengsheng, in charge of religious groups and ethnic minorities and the fourth-ranked leader in the ruling Communist Party, told officials at an event marking the 60th anniversary in the regional capital, Urumqi, not to rest on their laurels. “We must fully recognise that Xinjiang faces a very serious situation in maintaining long-term social stability, and we must make a serious crackdown on violent terror activities the focal point of our struggle,” Yu said, in a speech carried live on state television. China’s government has said it faces a serious threat from militants and separatists in energy-rich Xinjiang, on the border of central Asia, where hundreds have died in violence in recent years. However, exiles and rights groups have said China has never presented convincing evidence of the existence of a cohesive militant group fighting the government, and that much of the unrest can be traced back to frustration at controls over the culture and religion of the Uygur people who live in Xinjiang – a charge that Beijing has denied. Radio Free Asia, citing its own sources, said that when police officers arrived at the mine, attackers “rammed their vehicles using trucks loaded down with coal”. One police officer, Ekber Hashim, told the station: “Nearly all the workers who were not on shift at the time were killed or injured. “Some workers were sleeping, while others were preparing to work when the attackers raided the building after killing the security guards.” Reuters was unable to reach officials for comment. Such incidents are frequently reported in overseas media, but not confirmed by the Chinese government until days later, if ever.