BEIJING - BEIJING is implementing a range of new security measures, state media said on Friday, as the Chinese capital cranks up efforts to prevent any disruptions affecting the August Olympics.

The reports came a day after a top Olympic security official said the military would be involved in anti-terror efforts, and government confirmation earlier this week that China had introduce more stringent visa requirements.

Police have begun random night checks of motorists' documents and have been searching subway and bus passengers for flammable liquids, reports in the Beijing Youth Daily and Beijing News said.

Earlier this week, three people died when a bus in Shanghai burst into flames. Police have blamed the incident on flammable liquids being brought aboard the vehicle, but have given no other details.

Critics of China have accused it of playing up the terror threat to provide an excuse to crack down on dissent, but the US, Britain and Interpol have all issued travel warnings, saying the Games are a potential target for attack.

In comments quoted by Internet media, Olympic security official Tian Yixiang said on Thursday that the army, navy and air force would be employed to protect against such attacks.

'From the standpoint of Beijing Olympic security, the main danger is a terrorist attack from three possible threats: East Turkestan terrorists, Tibetan separatists and the evil Falungong cult,' Mr Tian said.

'East Turkestan' is the name many Muslim ethnic Uighur residents of the western Xinjiang region use for their homeland.

Over the past two months China has announced it broke up four separate 'terrorist' cells from Xinjiang, two of which planned Olympic attacks.

However, some observers have questioned the claims, with exiled Uighur leader Rebiya Kadeer saying China fabricated them to justify a crackdown on the Uighurs, a Muslim central Asian people who have long chafed under Chinese control.

Beijing also had previously warned of threats from Tibetan forces angered by China's crackdown on unrest in the Himalayan region and from Falungong, a spiritual sect suppressed by Beijing.

China's top law enforcement official last month told security forces to 'strike hard' against any threats to social stability and China said on Tuesday it had introduced tougher requirements for those seeking Chinese visas ahead of the Games to ensure a 'safe environment'.

China had already tightened up airline security after claiming that a hijack attempt by a Uighur 'terrorist' had been foiled in March. -- AFP