BEIJING _ A Chinese army officer warned Friday that Islamic separatists are the biggest threat to the Olympics, but a regional official played down the danger.

At a rare briefing one week ahead of the opening of the games, Sen. Colonel Tian Yixiang of the Olympics security command center told reporters the biggest threat came from "the East Turkestan terrorist organization"_ the government's standard term for jihadist groups seeking to establish an Islamic state in China's far western region of Xinjiang.

A secondary threat came from Tibetan separatists who the government accused of orchestrating a wave of violent protests in western China in the spring, Tian said.

"These forces are trying all means to sabotage the Beijing Olympic Games," Tian said, adding that a force of 34,000 soldiers has been positioned in Beijing and other Olympic host cities such as Shanghai to guard against such threats.

However, the deputy governor of the Xinjiang accused journalists of exaggerating the terrorist threat to the games.

"These terrorist groups are not as capable as some media organizations have claimed or broadcast," Kurexi Maihesuti told reporters in Beijing.

New terrorist concerns were prompted last week by videotaped threats purporting to be from an Islamic militant group claiming responsibility for explosions in four cities in western China in recent months, including two bus bombings in the city of Kunming that authorities said killed two people and injured 14.

But Maihesuti said many of those labeled terrorists were merely "lawless people."

Human rights groups have long accused Beijing of classifying many personal disputes or criminal acts as terrorism to justify harsh oppression.

Chinese authorities claim to have foiled a series of plots by members of Xinjiang's main Uighur ethnic group that it says targeted the Olympics, detaining 82 alleged Islamic terrorists and separatists in a major crackdown. Few details have been given and no evidence shown, although terror experts say insurgents based along the border with Afghanistan and Pakistan have a limited capability to launch such attacks.

Maihesuti said such groups were tiny in number and poorly organized.

"So you can see that these terrorist groups are not that capable of instigating massive sabotage activities as some hostile forces hope to see."

China has laid on massive security for the Aug. 8-24 games, as much to prevent protests by political or religious dissidents as to stop crime and terrorism. A 100,000-strong contingent of police and special forces are safeguarding venues, while hundreds of thousands of Beijing residents have been formed into voluntary security patrols.

Maihesuti said the government knew of only "around three to four" Xinjiang terrorist groups, and that government successes against their plots show their lack of effectiveness.

In the videotaped threats last week, one militant, identified by the Washington-based monitoring group IntelCenter as commander Seyfullah, warned athletes and spectators "particularly the Muslims" to stay away from the Olympics.

"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," he said.

Chinese police have played down the threat, saying the explosions in Chinese cities claimed by the group were not the work of terrorists.