Six members of China's Uighur minority tried to hijack a plane flying from a restive city in the far-western Xinjiang region on Friday but crew members and passengers thwarted them, authorities said.

The plane returned safely to the airport in Hotan city -- which has seen a spate of violent clashes between mainly Muslim Uighurs and police due to simmering ethnic tensions -- and the suspects were detained, authorities said.

"The six hijackers are Uighurs," Hou Hanmin, a spokeswoman for the government of Xinjiang told AFP.

"For the moment, we don't know the purpose of the hijack. It's still under investigation," she said, adding at least seven crew members and passengers had been injured in the incident.

Two security personnel were also seriously injured, the official Xinhua news agency said.

The aircraft took off at 12:25 pm (0425 GMT) from Hotan, then 10 minutes into the flight the six suspects tried to "violently hijack" the plane, according to tianshannet.com, the Xinjiang government's news website.

But crew members and passengers soon brought them under control and the aircraft returned to the city, the website said.

The plane -- which belongs to Tianjin Airlines, according to Xinhua -- had been bound for the Xinjiang capital of Urumqi, it added without providing further details.

Xinjiang is home to around nine million Uighurs, many of whom complain of religious and cultural repression by Chinese authorities -- a claim the government denies -- and the region is regularly hit by unrest.

The exiled World Uyghur Congress (WUC) disputed the government version of events, claiming that a fight over seating broke out onboard the aircraft between a group of Uighurs and Han Chinese, who vastly outnumbered them.

"The Uighurs of Hotan believe that this story about taking hostages is a lie," Dilxat Raxit, a spokesman for the organisation told AFP.

"We call on the international community to demand an inquiry. The Uighurs of Hotan believe the government is taking advantage of this incident to reinforce repression," he added.

Exiled Uighurs have accused authorities of launching a crackdown ahead of the anniversary of deadly July 2009 clashes between Uighurs and Han Chinese in Urumqi, among the most violent ethnic unrest in China in recent years.

Earlier this month, 12 children were injured when police raided an Islamic school in Hotan, amid the crackdown that has also targeted "illegal" religious activities.

Police said they descended on an "illegal religious study centre" on June 6 to free children being held there when criminal suspects "ignited a flammable explosive device".

They said officers had to fight to put out the fire, and 12 children suffering from burns were sent to hospital. Authorities have since launched house-to-house searches in the city.

The WUC, however,cited sources on the ground as saying police tossed tear gas into the school and caused the confrontation.

In July last year, at least 20 people -- including Uighur protesters -- were killed in Hotan in a clash with police.

State media quoted an official in the region as saying the clash was a "terrorist" attack and said four people including a police officer were killed when a crowd set upon a police station in the remote city.

But Uighur activists called it an outburst of anger by ordinary members of the minority, and accused authorities of attempting to block information on the deadly incident.

Xinjiang, a vast resource-rich region that borders Pakistan and Afghanistan, has been under heavy security since the July 2009 ethnic riots.

Rights groups say the violence in the region stems from long-held grievances among Uighurs, who complain of decades of repressive rule by Beijing and say an influx of Han is eroding their culture.

The government, however, says it has provided much-needed development to the region, and blames much of the violence there on what it calls the three "evil forces" of religious extremism, separatism and terrorism.