Despite tens of thousands of people across the country lending their support online and the campaign being widely reported in the media, not a single child has been rescued since it was launched on January 17.

A lack of evidence could be one reason, Zhang wrote in his microblog on t.sina.com. He complained that the police only asked the children whether the adults were their relatives instead of conducting further scientific investigations, such as comparing DNA.

Microblog creator Yu Jianrong, of the Rural Development Institute of the Chinese Academy of Social Sciences, hit upon the idea after he received a letter from the distraught mother of an abducted child.

Yu opened microblogs on t.sina.com.cn and t.qq.com, two popular Twitter-like services.

Since the microblogs were set up, more than 1,200 images of child beggars have been posted. The postings usually include the times and places where the children beg.

The microblogs have accumulated about 154,000 followers, including some local police officials.

Growing numbers of ordinary people are taking photos or videos for publication on the microblogs to help parents locate missing or abducted children.

But some supporters are beginning to wonder whether the campaign could have negative consequences for abducted children. Some said traffickers could also log on to find that the children they held have had their pictures published.

One said: "Would they run the risk of being caught by still taking the children to the streets, or would they abandon or kill them to protect themselves?"