A city in China's restive western region of Xinjiang has banned people with head scarves, veils and long beards from boarding buses, as the government battles unrest with a policy that critics said discriminates against Muslims.

Xinjiang, home to the Muslim Uighur people who speak a Turkic language, has been beset for years by violence that the government blames on Islamist militants or separatists.

Authorities will prohibit five types of passengers - those who wear veils, head scarves, a loose-fitting garment called a jilbab, clothing with the crescent moon and star, and those with long beards - from boarding buses in the northwestern city of Karamay, state media said.

The crescent moon and star symbol of Islam features on many national flags, besides being used by groups China says want to set up an independent state called East Turkestan.

The rules were intended to help strengthen security through August 20 during an athletics event and would be enforced by security teams, the ruling Communist Party-run Karamay Daily said on Monday.

"Those who do not comply, especially those five types of passengers, will be reported to the police," the paper said.

In July, authorities in Xinjiang's capital Urumqi banned bus passengers from carrying items ranging from cigarette lighters to yogurt and water, in a bid to prevent violent attacks.

Exiled Uighur groups and human rights activists say the government's repressive policies in Xinjiang, including controls on Islam, have provoked unrest, a claim Beijing denies.

"Officials in Karamay city are endorsing an openly racist and discriminatory policy aimed at ordinary Uighur people," Alim Seytoff, the president of the Washington-based Uyghur American Association, said in an emailed statement.

While many Uighur women dress in much the same casual style as those elsewhere in China, some have begun to wear the full veil, a garment more common in Pakistan or Afghanistan than in Xinjiang.

Police have offered money for tips on everything from "violent terrorism training" to individuals who grow long beards.

Hundreds have died in unrest in Xinjiang in the past 18 months, but tight security makes it almost impossible for journalists to make independent assessments of the violence.

About 100 people were killed when knife-wielding attackers staged assaults in two towns in the region's south in late July, state media said, including 59 "terrorists" shot dead by police. A suicide bombing killed 39 people at a market in Urumqi in May. – Reuters