By Michael Martina
BEIJING (Reuters) - Chinese extremists have joined the Islamic State and authorities have broken up gangs that returned from fighting abroad, the Communist Party boss of China's western Xinjiang region said on Tuesday, arguing that secrecy was needed to save lives.
China says militants who want to establish a separate state in Xinjiang called East Turkestan are holed up along the ungoverned Afghan-Pakistani border, and have expressed concern that fighters are traveling to battlefields in Syria and Iraq.
Around 300 Chinese extremists were fighting with the Islamic State, Chinese state media said in December, but officials have been vague about the extent of the threat. Such numbers are nearly impossible to verify.
"I believe Xinjiang has extremists that have joined IS," Xinjiang Communist Party Secretary Zhang Chunxian said at a briefing on the sidelines of China's annual session of parliament.
"Recently, we broke up a few cases involving those who had returned directly after fighting in war," Zhang said, without giving further details.
"To break the case, to reduce human loss and casualties and ensure security, sometimes you have to keep some things confidential for a time," he said.
The U.S. government and rights groups have urged China to be more transparent in its policing of what officials deem "terrorist" incidents in the region that have killed hundreds in the past two years.
Activists and exiled groups of Uighurs, a largely Muslim ethnic minority that calls Xinjiang home, say the government's repressive policies, including controls on Islam, have provoked unrest. Economic marginalization of Uighurs and curbs on their culture also lead to ethnic tension, they say.
A heavy security presence and limits on journalists' access there makes independent assessments of such violence difficult.
Xinjiang had paid an "enormous price" for stability and development, Zhang said, noting that the rate for the region's police officers "laying down their lives" was 5.4 times higher than for the rest of the country.
Dilxat Raxit, the spokesman for the exiled World Uyghur Congress, said in an email that remarks by Xinjiang officials "completely serve" China's domestic political needs.
"China continues to avoid the main factors behind conflict and dissatisfaction," he said.
(Reporting by Michael Martina; Editing by Nick Macfie)