Long queues snaked around Beijing airport yesterday as China imposed a nationwide Olympic Games security clampdown. Roads were closed, factories shut and teams of state-controlled volunteers deployed to sniff out and report "suspicious" behavior.

All who enter passenger terminals at Beijing Capital International Airport now face security screening. Special detectors - including US-imported paper which detects gunpowder - and sniffer dogs have been deployed. X-ray machines and anti-riot robots have been set up at checkpoints on highways leading to the airport.

The airport police's deputy director, Zhang Zhi, said the first day of checks went smoothly despite some overcrowding, which he blamed on people not queuing properly. Similar security measures were put in place at airports in 19 cities and regions, including Shanghai, Qingdao, Xinjiang and Tibet.

At Beijing's 11 long-distance bus stations, security was strengthened to prevent people from carrying explosives and knives on board. Long-distance buses have been banned from stopping en route to Beijing.

Young uniformed volunteers took to the streets, standing 100 meters apart to check on and report any suspicious behavior to the police.

"For example, we will stop members of the Falun Gong from handing out pamphlets," one said.

Private vehicles are only allowed to enter the city on alternate days, depending on the last digit on their license plates, with odd numbers banned on one day and even numbers on the next.

The ban is relaxed between midnight and 3am and is expected to move four million commuters to public transport. Violators will face a 100 yuan (HK$114) fine.

The fast lanes on highways and wide roads have been reserved for vehicles with permits. Anyone else will be detained and fined between 200 yuan and 1,800 yuan.

At the same time more than 50 cement factories in Beijing have been ordered to stop production. Five have been exempted to provide for emergency needs.

Ten bus lanes to the Olympic venues also started running yesterday.