Police shut down the bustling bazaar in the capital of China's restive Muslim region of Xinjiang on Friday amid threats from an Islamic group that attackers might target buses, trains and planes during the Olympics.

A sign at the entrance of the bazaar in Urumqi did not explain why the area, surrounded by mosques with minarets, was off limits as the country prepared to kick off the Summer Games thousands of miles away in Beijing.

Even a KFC restaurant in the shopping area — filled with touristy shops selling carpets and jade — was closed, and a guard sitting on the steps shooed people away.

The sprawling, far-flung western region of Xinjiang has long been a source of trouble for China's communist government. The rugged, mineral-rich territory is populated by the Uighurs, a Turkic Muslim minority that has had tense relations with the Chinese. Many Uighurs favor independence or greater autonomy for Xinjiang, which takes up one-sixth of China's land mass and borders eight Central Asian countries.

On Thursday, a videotape purportedly made by the Turkistan Islamic Party — a militant group seeking Xinjiang independence — was released with threats to launch attacks during the Olympics.

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"Choose your side," says the videotape's speaker, grasping a rifle and dressed in a black turban and camouflage with his face masked.

"Do not stay on the same bus, on the same train, on the same plane, in the same buildings or any place the Chinese are," he warns Muslims, according to a translation by the SITE Intelligence Group, a U.S. operation that monitors militant organizations.

The Turkistan Islamic Party is believed to be based across the border in Pakistan, where security experts say core members have received training from Al Qaeda.

Last month, the militant group issued videotaped threats and claimed responsibility for a series of bus bombings in China in recent months. The latest video features graphics similar to ones used earlier: a burning Olympics logo and an explosion imposed over an apparent Olympic venue.

The new video claims the communist regime's alleged mistreatment of Muslims justifies holy war. It accuses China of forcing Muslims into atheism by capturing and killing Islamic teachers and destroying Islamic schools, according to the SITE. It also says China's birth control program has forced abortions on Muslim women.

"I think what they're doing is they're trying to capitalize on the buildup to the games," said Ben Venzke of the Washington-based IntelCenter, which provides counterterrorism intelligence to U.S. government agencies.

Venzke said Friday that his group believes that based on the militant group's demonstrated ability to conduct bombings "and the apparent opportunity TIP believes the Olympic Games presents in terms of targeting and striking a blow to China, that the threat is credible and should be taken seriously."

He said the release of a five-page written threat, in conjunction with two videos over the last three months by the group "is indicative of an orchestrated campaign designed to fulfill jihadists belief that they should provide warning before launching a significant attack."

More than 100,000 soldiers and police are guarding Beijing and other Olympic co-host cities. Terrorism experts say the heavy security presence would likely force attackers to target less-protected areas.

Beijing's iconic Tiananmen Square was mostly closed off to visitors much of Friday as Chinese President Hu Jintao hosted world leaders at a luncheon banquet at the Great Hall of the People ahead of the opening ceremonies.

"I think the actual Olympics themselves, the venues, the guests, the athletes, are going to be safe," said Drew Thompson, director of China studies at the Nixon Center in Washington. "I would not be an alarmist."

Thompson added that Uighur groups haven't demonstrated they have the capacity to attack Beijing or other host cities during the games.

On Monday, assailants killed 16 border police and wounded 16 others in the Xinjiang city of Kashgar when they rammed a stolen truck into the group before tossing homemade bombs and stabbing them. Chinese authorities called the raid a terrorist attack and said they had arrested two men who are Uighurs.

Authorities have called the men terrorists, but officials have released no evidence linking them to a specific group.

Xinjiang's capital, Urumqi, has been on high alert. Security guards were checking bags at the entrances of hotels, department stores and discos in the busy city, which unlike other Xinjiang cities is predominantly Han Chinese — the nation's largest ethnic group. In the past 50 years, Han Chinese have been flooding into the region, creating another sore point with the Uighurs.

Xu Zhongcheng, an expert on counterterrorism and organized crime at Shandong Police College in eastern China, said security experts were taking the threats seriously, though more as "psychological warfare than real acts."

He added, "The more terrorist threats, the more closely the Chinese people will stick together."