Police?in Shanghai?have begun using sniffer dogs at subway stations in a bid to increase passenger safety ahead of the Olympics.

With traveler numbers expected to increase dramatically on the approach to the Games, about 40 dogs will be used across the city to sniff out flammable products, such as oil-based paints and firecrackers, which could pose safety risks, police said.

On March 28, the first day the dogs were used, more than 70 passengers were found to be carrying forbidden items, mostly fireworks, police said.

Firecrackers and oil-based paints are the most commonly found illegal items, they said.

Passengers who are found to be carrying large quantities of banned materials, such as glue, gas and paint, will be asked to leave the station, police said.

Despite complaints from some subway passengers, the new security checks have been well received by most people.

Wu Yu, an office clerk who commutes every day on the subway, said: "Despite it being a bit troublesome having to stop to have my bags checked, the move is necessary for passenger safety."

Wang Lin, another commuter, agreed.

"Passengers should show their support for the security effort," he said.

Some commuters, however, expressed concerns about being approached by dogs.

"Dogs that patrol subways should be able to detect dangerous items without touching passengers' clothes," commuter Zhang Ying said.

"They could frighten some people, especially children and those who dislike dogs."

A police spokesperson tried to allay people's fears.

"We use only small breeds like spaniels that are used to being around people. Also, all the dogs have been trained to be relaxed and calm in the crowded environment of a subway station."

The spokesperson did not say how long the dogs will remain a fixture on the metro.

Since 2006, dogs have been helping police in Shanghai to detect dangerous substances at airports, subways, railway stations and shopping malls. This year alone, more than 300 people have been investigated for carrying hazardous materials, the city's police bureau said.

Shanghai's metro system is one of the busiest in the world. On Thursday, it broke its passenger record for a single day with traveler numbers hitting 3.71 million.

(China Daily May 6, 2008)