A policewoman checks a passenger's bag at a subway station in Beijing yesterday. [China Daily]

More than 2,000 security guards have been deployed and 200 X-ray baggage machines have been installed at all 93 subway stations in Beijing as part of tightened security for the Olympics and Paralympics.

The comprehensive security check was introduced on Sunday covering 181 checkpoints in the subway, and will last until Sept 20.

The move follows a slew of measures earlier this year to safeguard security in the subway. More police were deployed, including sniffer dogs.

More than 100 prohibited items had been seized up to 10 am yesterday.

On subway line 13 of Wangjing West station, a passenger was stopped while trying to board a train with 2 kg of petrol.

Subway regulations ban the carrying of guns, ammunition, inflammable and explosive liquids, knives, and radioactive and poisonous materials.

"Passengers who refuse security checks or insist on carrying prohibited articles will not be allowed to board trains, and could face punishment," a policeman at Changchunjie station said.

The Law on Public Security Administrative Penalties stipulates that those who take flammable or explosive goods onto public transport can be detained for between five and 15 days.

"The most commonly found prohibited items these days is alcohol, but most of it is within the limit of 2 kg," the policeman said.

As visitors to military museums are fond of buying fake ammunition or toy guns as souvenirs, metro staff suggested they should have invoices for their purchases when boarding trains.

To ease concerns of worsening congestion during rush hours, extra police will be on hand at entry and exit points.

"It won't take much time for passengers to go through the security check, as an inspection of a bag takes less than 10 seconds," the policeman said.

Most commuters welcomed the tightened security.

"As the Olympic Games draws near, security should come first," a passenger, Xiao Chen, said.

He was asked to drink a mouthful of the bottled water he was carrying in his bag.