Last summer, the couple earned 5,000 yuan after taking her to beg in Nanjing for a month. Last autumn, the couple earned another 10,000 yuan in two months from her and then spent the money on their son's wedding, said the government.

Meanwhile, thousands of pictures of children begging on the street and on subways have been posted online since a nationwide campaign was launched last month to save child beggars. However, the more pictures there are, the more difficult it is for parents to find their lost children.

Scientists said yesterday that China's leading face recognition technology is to be used to assist the campaign.

With this technology, parents could immediately find lost children among the tens of thousands of uploaded photos, said Li Ziqing of the Chinese Academy of Science.

Li's research team, which provided the face recognition technology for the security systems at the Beijing Olympics 2008 and the Shanghai World Expo last year, is to apply the technology to finding lost children. The platform is due to be launched next week, Li said.

"With our technology, pictures with identical faces can be matched from millions within three seconds." Li said.

The system will be supported by Baidu.com, the biggest search engine in China, and also by sina.com as the latter's microblog has been playing a significant role in the campaign.