Thousands of children unaccounted for since Haiti’s earthquake are at risk of falling prey to child traffickers, aid agencies have warned, as fears were raised over at least 15 children who have vanished from hospitals within the past few days.

Unicef, the UN children’s agency, warned that “traffickers fish in pools of vulnerability. We know from past experience that trafficking happens in the chaos that usually follows emergencies.” A Unicef adviser, Jean Luc Legrand, said he knew of at least 15 cases of children disappearing from hospitals.

Save the Children, World Vision and the British Red Cross have called for an immediate halt to adoptions of Haitian children not approved before the earthquake, warning that child traffickers could exploit the lack of regulation. There has been a surge in offers from well-meaning foreigners.

The scale of the problem is potentially enormous. Haiti is awash with children, with 45 per cent of its population younger than 15. One UN official estimated that between 40,000 and 60,000 children were killed, orphaned or separated from their families by the earthquake, which struck while most were still in school, and anecdotal evidence suggests many have been left to fend for themselves. A UN official spoke of people driving to the airport in expensive cars and putting children on outgoing flights without any documentation.