Delegates at an international conference on human trafficking have called for rich countries to relax their immigration and labour policies to provide more safe and legal channels for those seeking work. Economic migrants, especially women, would turn to smugglers to help them migrate unless there were more programmes to allow them to leave their home countries legally, said Noeleen Heyzer, head of the United Nations Development Fund for Women. 'All they know is that there is an offer of a job somewhere, in some distant place,' she said. Delegates in Hawaii said women and children who agreed to be smuggled were put in a vulnerable position and ended up being trafficked against their will, then sold for labour or sex work. Estimates of the number of women and children trafficked each year range from 700,000 to four million, although some advocates and academics questioned the data and urged more research. The United States and European Union countries are often destination countries for such migrants, although movement also occurs between Southeast Asian nations. Thailand and Cambodia will co-operate on repatriating 88,000 undocumented Cambodians living in Thailand. Cambodia is negotiating with Vietnam on a similar agreement over illegal Vietnamese migration to Cambodia. It is hoped to criminalise the trafficking, and set up programmes to help migrants. Some delegates called for more accountability from countries such as the US, where the CIA estimates there are 50,000 smuggling cases each year. The US deputy secretary for health and human services, Claude Allen, said the government would hold companies that sold contracted goods or services to the US government more accountable for their treatment of workers abroad. 'It has been a blind spot. We said that's not for us [to regulate].' Some delegates questioned whether similar economic development programmes could be effective in all cases of trafficking. Phil Marshall, of the UN Interagency Project on Trafficking, said most aid focused on areas where illegal migrants originated from, but more needed to be done to understand the places where there was demand for these migrants' labour. He said: 'If the demand market is not changing, and you're not doing anything about the traffickers, you're just going to have other people being trafficked in their place.'