When Wang Bangyin tried to hug his son, the three-year-old boy dodged behind a policeman and cried in fear.

With eyes welling with tears and face twisted in pain, Wang sobbed silently. His life had been a nightmare since the boy was abducted two years ago.

"I dreamed of him everyday and cannot believe that I could really see him again," said the 51-year-old man.

Wang's nightmare started on October 26, 2007 when all of his three sons (two older stepsons) disappeared suddenly. The three boys, aged 15, 6 and eight-month-old respectively, were abducted while playing outside Wang's rented house in Guiyang, capital of southwest Guizhou Province.

The boys were grabbed by several men and carried away by a motorcycle. On hearing people's cry, Wang's wife rushed out of house and chased more than 300 meters only to see the motorcycle disappearing in distance.

After calling the police, Wang and his relatives embarked onto a journey searching for the kids. They searched all the bus and railway stations in Guiyang, and spent almost all their meagre saving on printing and posting missing notices in the city.

One month later, police found Wang's eldest stepson, who was sick and thus was abandoned by the child traffickers. But the boy had no idea of the whereabouts of his two brothers.

Wang had basically stopped working after the boys were abducted. "I had no mood for working. Whenever I saw kids of similar age of my boy, I couldn't help crying," said Wang, who used to make a living by working at construction sites.

In Guiyang, Wang's misery was not unique. In the Nanming district of Guiyang alone, 17 children have been reported missing since 2007.

Local police said that the mountainous Guizhou Province is a transfer stop in the underground child trafficking network.

"Most of the kids were abducted from southwestern provinces like Yunnan, Guizhou and Sichuan, and sold to the north or east provinces like Fujian, Shandong and Hebei," said Xu Jun, an officer with the Nanming branch of the Guiyang police bureau.

In China, many people, especially those in rural areas, still prefer boys to girls so as to carry on the family name.

There was no statistics as how many children were abducted every year, but experts estimated that the figure could be between 30,000 and 60,000, according to earlier Xinhua reports.

Since April 9 this year, China's Public Security Ministry has launched a campaign to crack down child abduction and trafficking. A total of 2,169 children have been rescued as of October 28 and 1,358 traffickers were arrested.

Xu said many kidnappers were middle-aged men and their targets were mostly children of the migrant workers living in the suburban areas.

Most of the migrant workers were busy making a live and unfamiliar with the new environment in the city. "Besides, growing up in the countryside, they are used to letting their kids play outside alone, which gives criminals chances," Xu said.