Security has been tightened in China's troubled Xinjiang Uyghur Autonomous Region after reports of violence in the central and southern parts of the region, sources said Tuesday.
An exile group said that several dozen ethnic Uyghurs had been rounded up following the incidents in the region.
Unidentified men attacked a police station in Hotan prefecture in the south of Xinjiang on Saturday, unconfirmed reports have said, and two days earlier, deadly violence was reported between ethnic Uyghurs and Han Chinese in central Xinjiang's Korla city in which, according to official Chinese media, four people were killed and eight others injured.
A security alert has also been placed in the west of Xinjiang where no clashes or attacks have been reported, with a curfew declared in the city of Aqsu, a resident said.
A police officer in Xinjiang told RFA's Mandarin Service that the Xinjiang authorities have activated a "first degree response plan,” suggesting that the region has been placed on the highest level of red alert.
A Uyghur resident in Hotan city said police patrols and spot checks have been beefed up.
“Many more armed police are now patrolling the streets day and night. They check IDs for both Han Chinese and Uyghurs,” the resident, identifying himself as Mamat, said.
Police and residents were however unable to confirm a weekend report by the Hong Kong-based Information Centre for Human Rights and Democracy that unidentified men had staged a gasoline bomb raid on a police station in Gujiang Bage township in Hotan on Saturday.
“No, there were no such attacks,” a police officer who answered the phone at the station said. "Are you a reporter? These would be rumors spread on the Internet,” he claimed.
The Hong Kong center had said that the attackers had placed nails at the police station’s entrance to prevent police cars from leaving the station in pursuit of them after the bombing raid.
A Xinjiang netizen, quoting a reliable source, said on China's Twitter-like social media platforms that many armed police were seen at airports and other key transport hubs in the region and that security was very tight.
A worker at a motel near the police station said heavy police presence was reported in the area.
“There are checkpoints and roadblocks everywhere around here. Even if you want to stay in hotels, you have to be checked."
Dilxat Raxit, Munich-based spokesman for the exile World Uyghur Congress, said he was informed that security in the southern part of Xinjiang has been tightened.
"We learned from various sources that several dozen Uyhgurs have been arrested" following the incidents," he said.
In Aqsu, a resident said the city has been put under curfew from 1 a.m. to dawn.
“The police check IDs for both Han Chinese and Uyghur. Army troops and armed police are patrolling the streets 24 hours a day,” a Han Chinese resident surnamed Wang said.
“Before 1:00 in the night, all residents must return to their own homes, and you cannot go out until dawn.”
“If they find you on the streets they will take you away to question,” he added.
Few details were available on Thursday's violence in Korla city, with some reports suggesting the incident could have been sparked by a gambling dispute or by a knife attack by ethnic Uyghurs.
Regional spokeswoman Hou Hanmin said the attackers were Uyghurs, one of the assailants had been detained, and police were searching for the others, Agence France-Presse reported.
She did not identify the ethnicity of the victims, or state whether the attack was politically motivated.
Violence between Han Chinese and Uyghurs rocked the Xinjiang capital Urumqi in July 2009, in China’s worst ethnic clashes in decades.
The clashes prompted a harsh crackdown in the Xinjiang region, where Uyghurs chafe under Beijing’s rule and say they have long suffered ethnic discrimination and oppressive religious controls.
Reported by Qiao Long for RFA's Mandarin Service. Translated by Ping Chen. Written in English by Parameswaran Ponnudurai.