Chinese authorities on Saturday denied claims by a Uygur separatist group that it took credit for a series of attacks in different Chinese cities, including deadly bus explosions in Shanghai and Kunming.
A group calling itself the Turkistan Islamic Party had released a video threatening next month's Beijing Olympic Games, according to AFP and Reuters, citing the IntelCenter, a Washington-based terrorism monitoring firm.
The group also claimed responsibility for several other incidents. These included an attack on police in the eastern city of Wenzhou, Zhejiang Province, on July 17 with an explosive-laden tractor and the bombing of a plastics factory in the southern city of Guangzhou, Guangdong Province, on the same day.
China's Ministry of Public Security declined to comment on Saturday when contacted by Xinhua, but police authorities in Shanghai, Yunnan, Zhejiang and Guangdong refuted the claims.
Shanghai police reiterated on Saturday that the May 5 bus blast in the Olympic co-host city had nothing to do with "terrorist attacks."
An investigation showed the blast, which killed three people and injured 12, was caused by inflammables such as oil, said ChengJiulong, Shanghai Municipal Public Security Bureau deputy head.
"The blast was indeed deliberate but had nothing to do with terrorist attacks," he said.
Two of the dead were local female residents. Police have yet to confirm the identity of the male victim. They have offered a 50,000 yuan (7,350 U.S. dollars) reward for information about the man.
Cheng didn't provide further details about the latest development of the case.
He said on Wednesday Shanghai police had cracked a terrorist group who planned to attack an Olympic football preliminary venue in the city.
"We have obtained information that international terrorist organizations would likely launch an attack against an Olympic venue in the city during the Games.
"We have staged raids and cracked a group of terrorists." But he didn't provide further details such as when the terrorists were detected, how many suspects were detained and where they came from.
In another case, two explosions occurred about an hour apart on two buses during the morning rush hour on Monday in Kunming, capital of southwestern Yunnan Province, leaving two dead and 14 injured.
"We have noticed media reports about the claims, but so far no evidence has been found to indicate the explosions were connected with terrorists and their attacks, or with the Beijing Olympics," a Yunnan Provincial Department of Public Security spokesman told Xinhua on Saturday.
"As to whether the explosions were masterminded by many suspects or just an individual, there is no conclusion now," he said. "The investigation is continuing."
Local police have tripled the reward to 300,000 yuan for information that could help to solve the two blasts.
In a related development, police in the eastern city of Yangzhou on Thursday detained a 23-year-old vegetable peddler surnamed Wang who had claimed responsibility for the two explosions and threatened to carry out more in future.
Wang said during a police interrogation he made the acts with the purposes of getting more, stronger attention and worship from netizens.
But his "confession" was questioned by police and media, because he was very frivolous during the interrogation and impudently called himself a "newsmaker."
"I just did it (the explosions) for fun. That can arouse the attention of the great masses of the on-line people. I don't think my acts have broken the law," he was quoted as saying by the Yangzi Evening News in Yangzhou on Saturday.
Zhejiang police dismissed the separatist group's claims as "nonsense."
"There was definitely no such violent attack against police in the whole province on July 17," a Zhejiang Provincial Public Security Department spokesman said.
According to the description of an explosives-laden tractor in the Wenzhou blast as claimed by the separatist group, the incident happened on May 17 instead of July 17 -- and it was not targeted at police.
The May explosion that killed 17 in what was originally thought to be a traffic accident was in fact caused by a disgruntled gambler plotting revenge with an apparent bomb attack.
"Nonsense! The explosion totally had nothing to do with terrorist groups," Chen Shichun, the Wenzhou Municipal Public Security Bureau head, said.
Chen said Hu Baoqiang, 44, had driven a tractor carrying a tank of gas and explosives to a gambling den. This appeared to be a planned attack after he had lost money gambling.
The explosion occurred outside a small building alleged to have been a local gambling den when the tractor was involved in a collision with a car and a minibus.
Forty people were injured, including those in the alleged gambling den, bus passengers and passersby.
Hu was also killed in the blast in Longwan Village of Wenzhou's Longwan District.
The man was the boss of an illegal local quarry and this was why he had explosives, Chen said.
Also Saturday, the Guangdong Provincial Public Security Department told Xinhua that "there was no terrorist attacks on July 17 in Guangzhou."
According to global intelligence analysts Stratfor, the Turkistan Islamic Party is another name used by the Eastern Turkistan Islamic Party, AFP reported on Saturday.
The Eastern Turkistan Islamic Party is also known as the ETIM, or the Eastern Turkistan Islamic Movement.
The United States, China and other countries have designated ETIM a terrorist group. They are an ethnic Uygur and Muslim separatist group seeking to create an independent state in northwest China's Xinjiang Uygur Autonomous Region.
Xinjiang police said on Saturday they had noticed the group's claims.
"We will continue to keep a close watch over the social situation in Xinjiang and strive to ensure Olympic security," a Xinjiang Autonomous Regional Public Security Bureau spokesman said.
"We have dispatched hundreds of police officers who can speak Uygur ethnic language to major cities in other provinces this year to assist in ensuring local social stability," he said.
Xinjiang police were also working with their counterparts in Yunnan to investigate Monday's bus explosions, he added.
Local police said earlier they had cracked five terrorism groups in the first half of 2008 in Xinjiang, detaining 82 suspected terrorists who allegedly plotted sabotage against the Olympics.
With the Games set to open in less than two weeks, safety has become China's No. 1 issue; the public has also gradually shifted its focus from the "best Games in history" to the more pragmatic "safe Games."
"A safe Olympics is the premise for a first-class Games with Chinese characteristics. Safety is our top concern here," Vice President Xi Jinping said on Monday during a visit to the Games' command center and several event venues.
It was the second time for Xi to stress safety, following his call on July 15 in Qinhuangdao of the northern Hebei Province that Olympic venues outside Beijing should give priority to safety.
Zhou Yongkang, a member of the Standing Committee of the Political Bureau of the Communist Party of China Central Committee, and Meng Jianzhu, Minister of the Public Security, also underlined earlier this month that the security for the Olympics is in a key phase, and the public should be mobilized to contribute to it during the Games.
Chinese police believe the Games are facing three major threats: planned attacks by international terror groups against specified countries and personnel, the ETIM and violent criminal acts.
Beijing's tight security measures could be easily sensed as the Olympics draws near. From anti-terrorism drills to the halting of flights during the opening ceremony, the city is taking every possible measure to ward off potential security threat.
Peripheral fences now encircle all Olympic venues, the Olympic Village and the Olympic headquarters hotels. Monitoring and alarm facilities have been installed with personnel and vehicle security checkpoints set up.
Armed police with dogs began round-the-clock patrols at the capital's four railway stations, including a renovated one in a southern district that hasn't yet opened. Air, rail and long-distance bus facilities are also on heightened alert.
"All work related to Olympic security is in full swing and security personnel and equipment are all in place," Liu Shaowu, director of the Beijing Organizing Committee for the Olympic Games (BOCOG) Security Department, told reporters on Wednesday.
He said Beijing had deployed nearly 110,000 personnel, including police, army troops and volunteers, and mobilized the whole society to ensure the Games' security.
"Beijing is confident of dealing with any kind of security threat and will present the world a safe and peaceful Olympics."