(Adds details of response, background)

BEIJING, July 26 (Reuters) - Chinese authorities have denied claims by a group calling itself the Turkistan Islamic Party that it was responsible for a series of bombings ahead of the Olympics, the official Xinhua news agency reported on Saturday.

The group released a video threatening the Beijing Olympics and claiming responsibility for deadly bus blasts in Shanghai and in Kunming, capital of the southwestern province of Yunnan, a terrorism monitoring firm in Washington said on Friday.

China's Ministry of Public Security declined to comment on Saturday, Xinhua said, but police authorities in Shanghai and in Yunnan, Zhejiang and Guangdong provinces dismissed claims that the bombings were linked to the group.

The Shanghai blast on May 5, which killed three people and wounded 12, was caused by inflammables such as oil, Cheng Jiulong, Shanghai Municipal Public Security Bureau deputy head, was quoted by Xinhua as saying.

"The blast was indeed deliberate but had nothing to do with terrorist attacks," he said.

IntelCenter, a U.S.-based terrorism monitoring firm, said the little-known Turkistan Islamic Party had released a video entitled "Our Blessed Jihad in Yunnan", featuring a statement by the group's leader, Commander Seyfullah, threatening next month's Olympics.

"Despite the Turkistan Islamic Party's repeated warnings to China and the international community about stopping the 29th Olympics in Beijing, the Chinese have haughtily ignored our warnings," IntelCenter quoted Seyfullah as saying.

Seyfullah said the group bombed two public buses in Shanghai on May 5 and "took action against police" in Wenzhou on July 17 with a tractor loaded with explosives.

MORE ATTACKS THREATENED

The group also bombed a plastics factory in Guangzhou on July 17 and bombed three public buses in Yunnan on July 21, according to the claims relayed by the IntelCenter.

Bus explosions killed at least two people and wounded 14 in the southwestern city of Kunming on Monday.

"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.

The Islamic group warned there would be more attacks on the Beijing Games.

"Our aim is to target the most critical points related to the Olympics. We will try to attack Chinese central cities severely using the tactics that have never been employed," Seyfullah said, according to the IntelCenter transcript.

On Thursday, Shanghai police said they had broken up an international terrorist group that had planned to attack an Olympic football preliminary match in the city, but gave no details about the group or the alleged attack.

Chinese officials have said their main Games security worries focus on separatist militants seeking an independent Uyghur homeland in the country's far west Xinjiang region and campaigners for an independent Tibet.

"Turkistan" is a name sometimes used by Muslim separatists for Xinjiang. The region's population is largely made up of Muslim Uyghurs, who have a Turkic language and culture. (Reporting by Ken Wills in Beijing and Deborah Charles in Washington; editing by Andrew Roche)

AlertNet news is provided by