BEIJING - An anti-terrorist force of nearly 100,000 commandos, police and army troops was on high alert for handling terrorist attacks before and during the Beijing Olympic Games, officials said 50 days ahead of the opening ceremony.

"Experiences of past Games show that terrorist attacks may occur before the Games, so our anti-terrorist forces have been in action ahead of the opening ceremony," said Liu Shaowu, the Beijing Organizing Committee for the Olympic Games (BOCOG) security department director.

The end of a series of anti-terrorist drills dubbed "Great Wall 5" at the national level earlier this month marked the beginning of the anti-terrorism campaign, he said.

The drills, including missions to deal with a chemical attack, hijacking athletes' buses and other possible contingencies, were staged from June 11 to 14 to test the city's emergency response capacity and smooth the coordination among various forces.

China has put an emphasis on security and stability in the run-up to the August Games as Chinese leaders have said terrorism constituted the biggest threat to the Olympiad.

Government officials said the forces prepared to deal with terrorist attacks during the Olympics comprised three parts -- security guards at sporting venues, security forces of the capital and national professional emergency forces.

"We have finished more than 52 schemes and more than 500 specific plans for security, transportation, fire-fighting, anti-terrorism and VIP protection," Liu said.

Among the forces was a Snow Wolf Commando Unit (SWCU), a highly-classified special police squad established in 2002.

The 300-strong unit was tasked with counter-terrorism, riot control and other special tasks, such as anti-hijacking and bomb disposal. Each officer of the unit was outfitted with 300,000 yuan (42,900 U.S.dollars) worth of equipment.

Beijing also has been stepping up international cooperation as the Games approach.

"We will cooperate with Interpol during the Games and inform every participating country of the security conditions every day," said Kong Bo, a commander center officer for the Games.

"China is a very, very difficult country for a foreigner to operate in without him, or her, or that group being detected," the Interpol head Ronald Noble was quoted by Reuters as saying.

Officials of the the Federal Bureau of Investigation (FBI) of the United States said the bureau was willing to offer its expertise to China on security issues relating to the Games. Police from France, Britain, Australia and Israel also exchanged ideas with the Beijing police.

The capital also has 150,000 security personnel and more than 290,000 volunteers patrolling every corner of the city to ensure a terrorism-free Games.

"We will never allow the terrorists to attack the Games. I will stop them once I have found any clue," said Li Gaoxiang, a 70-year-old professor patrolling on the street. "Scaring away thefts is also a contribution to the Games."

"The force of the police is limited, but the force of the people is limitless. The people is the backing of the security work for the Games," said Ma Zhenchuan, Beijing Public Security Bureau director.

More than 7,300 college students who have been trained and passed the tests, will participate in the security checks at the entrance of each venue, he said.

"Beijing will host a safe Games," said Liu, the BOCOG security official, "The confidence comes from our efforts."

"We are very well prepared for the Games," a SWCU officer said. "But I hope we will never have a chance to fire a shot."