A Human Rights Watch report has found acid attack victims in Cambodia are being denied the free healthcare required by law, and are often refused urgent treatment until they prove they can cover costs.

Though a 2012 law has helped to curb the number of attacks by limiting the availability of acid, it is still possible to acquire the harmful substances from markets, motorbike repair shops and rubber plantations for as little as $1 a litre.

Health Ministry spokesman Ly Sovann told the ABC all public hospitals were required to treat acid attack victims free of charge, but he declined to comment when asked why survivors reported they had been denied free healthcare.