BEIJING -- Police dogs began regular patrols in Beijing's crowded subway stations on New Year's Day, sniffing for incendiary substances carried by passengers.

"The police dogs have been trained to be comfortable with the crowded environments and slippery surfaces of subway stations," said Wang Ning, a deputy head of the detection detachment of the Beijing Traffic Police Division of the Beijing Public Security Administration.

He said eight dogs are on patrol at five downtown subway stations, including those that serve the central landmark, Tian'anmen Square.

"More dogs will join the patrols later. We only use small species, such as Labrador retrievers and spaniels, for their communications and people skills," said Wang.

The administration has stepped up attempts to detect any incendiary devices or explosives that might be carried in public places.

Firecrackers and oil-based paints are the flammable products most often seized by the police on public transport. Fireworks are considered a must by many Chinese for festival celebrations, especially for the coming Spring Festival, or Lunar New Year, which will fall on February 6.

The security patrol ahead of the festival will be good practice for the police dogs ahead of the Beijing Olympic Games later this year, said Wang.

The subway network in Beijing is one of the world's busiest; it set a new record daily ridership of 2.89 million passengers on November 16, 2007.

The capital city has been using sniffer dogs to detect drugs in public places, such as the airport, subway and railway stations and shopping malls since June 2007. But local residents are not familiar with regular dog patrols in public places.

Wang advised people to keep their distance from the dogs and not try to pet or feed them.