She said volunteers have been handing out leaflets and making speeches about the problem prior to today.

"I hope people call the police immediately if they see a child with unclear origins," she said.

Cheng also wishes more media outlets would take an interest in the problem.

"Our volunteers went to Beijing and tried to convince some TV stations like China Central Television to create a special program about missing children, but failed," Cheng said.

Some advocates suggested the need for more stringent regulations and laws to address the issue.

Liu Baiju, a member of Bureau of Scientific Research Management of the Chinese Academy of Social Sciences, said fixing loopholes in the current law is a more important issue.

"People who purchase trafficked children should be fined and get jail terms; otherwise, it would be hard for them to learn a lesson," Liu told the Global Times Monday.

According to the current law, a family that buys children faces no punishment if they return the children.

Police investigated more than 3,500 cases related to child trafficking as of May 10, part of a special operation to address the problem, according to the Ministry of Public Security.

The mission cracked 1,961 gangs and resulted in 12,427 arrests.

At least 4,743 children were recovered.