The United States has added Vietnam, Cambodia, Brunei and Macau to a human trafficking blacklist that already includes Malaysia, alleging weak efforts to stop forced sex work or assist migrant labourers.

In Cambodia, the State Department said that “endemic corruption” has impeded efforts to help thousands including children trafficked to entertainment establishments, brick kilns and online scam operations.

“Authorities often overlooked, denied or downplayed labour abuses – including forced child labour – in factories and at brick kilns and colluded with brick manufacturers to arrest, jail and return indentured labourers who had attempted to escape,” the report said.