Muslim Uighur fighters trained by the Islamic State in Iraq have vowed to plant the jihadists' black flag in China promising that the country will "flow in rivers of blood".

In a video released on social media and authenticated by the SITE terror monitoring website, the ethnic Uighur fighters in Iraq from western China's Xinjiang region vow revenge against the country's communist government in a half-hour long video.

In the footage, which shows the Isis fighters from the majority Muslim ethnic group training, one shot shows an image of Chinese President Xi Jinping followed by a burning Chinese flag.

"Hey, brothers. Today, we are fighting with infidels across the world. I'm telling you this: Don't be complacent in this. Stay strong," one of the fighters says, according to Uighur speakers who analysed the video for Reuters. "We will certainly plant our flag over America, China, Russia, and all the infidels of the world," he says.

Another fighter refers to the "evil Chinese Communist infidel lackeys". He adds:"In retaliation for the tears that flow from the eyes of the oppressed, we will make your blood flow in rivers, by the will of God."

The Chinese government has expressed concern over Uighurs who have fought for the Islamic State in Iraq and Syria, travelling illegally to the region via Southeast Asia and Turkey.

In 2015 the Islamic State released footage showing the execution of a Chinese hostage, consolidating fears Uighurs fighters have been travelling to the Middle East.

Unrest and discontent has been stoked in Xinjiang in the past few years as hundreds of people have been killed in unrest predominantly between Uighurs and ethnic majority Han Chinese. Beijing has consistently blamed the unrest on Islamist militants.