Three Chinese extremists who attempted to desert the Islamic State (Isis) in Syria and Iraq have been executed in the past six months, according to state-run Chinese tabloid Global Times.

The paper, which is affiliated to China's Communist Party mouthpiece the People's Daily, cited an unnamed Kurdish official as saying the three were killed in an escape attempt from the jihadist group over two separate occasions.

The militants were reportedly all Uighur Muslims from the restive northwestern region of Xinjiang and belonged to the East Turkestan Islamic Movement, a rebel group attempting to create a separate state in the region.

One militant was detained and shot dead as he attempted to flee the Islamist group and return to Turkey to attend university.

"He was a young man full of ideas who had recently arrived in Turkey. He felt disappointed about the reality of Islamic State after sneaking into Syria," the Kurdish official said.

The militant was caught after a Libyan companion reported him to his supervisor.

The other two were beheaded in December last year on treason charges, along with 11 others of different nationality. They were all trying to leave Syria.

China's special envoy to the Middle East, Wu Sike, revealed last year that the Middle East had become a training ground for militants from the Xinjiang region.

Around 100 Chinese militants are believed to be operating in the region.