The Mirror Foundation, an NGO in the North which helps families with missing children, yesterday submitted a change.org petition with more than 27,000 signatures to a Royal Thai Police Office adviser.
The petition calls on police to better investigate missing persons cases.
The move was spurred by the case of confessed killer and rapist "Nui", who admits he has abducted, abused and killed many children, including a six-year-old girl "Nong Cartoon'', his latest victim.
The activists also asked police to work more closely with the Ministry of Social Development and Human Security and the government, to better publicise missing persons reports.
Pol Gen Charamporn Suramanee, the police adviser who received the petition, said the Royal Thai Police Office had set up a centre to handle cases of missing persons and unidentified bodies.
The centre was developing ways to disseminate missing persons information to the public. Its hotline number is 1599.
Pol Gen Charamporn promised police would be more active in dealing with missing persons cases.