A city in northwestern China's Xinjiang region has banned people with large beards or Islamic clothing from boarding buses, state media has said.

Authorities in Karamay banned people wearing headscarves, veils, niqabs, or clothing with the Islamic star and crescent symbol from taking local buses, the ruling Communist Party-run Karamay Daily said on Monday.

The Karamay ban was intended to help strengthen security during a sports competition ending on August 20, the report said.

Xinjiang is home to the Muslim Uighur people who speak a Turkic language.

Rights groups say restrictions on Uighurs' religious and cultural freedoms have stoked tensions.

Exiled Uighur groups and human rights activists say the government's 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 a statement.

The report came days after the government-appointed head of the largest mosque in China, in one of the region's oldest cities, Kashgar, was killed after leading morning prayers.

Hundreds have died in unrest in Xinjiang in the past 18 months.

Last month, China banned Muslim officials and students from fasting during the month of Ramadan.

China announced a year-long nationwide "terrorism" crackdown following a deadly bombing attack in Xinjiang's capital Urumqi in May.

Source: Agencies