The Australian Christian Lobby has rejected WA Government claims that prostitution couldn't be better controlled, as being demanded by some back benchers.

"Sweden, Korea, Iceland and Norway have proven that is not the case," said Managing Director Jim Wallace.

Mr Wallace said ACL supported moves to amend the proposed law to allow a Swedish model which criminalises the purchase of sex.

"All state governments in Australia must realise the well documented link between legalised prostitution and sex trafficking, and move to control the industry,” he said.

ACL brought the documentary Nefarious to Australia last month, which exposes the hell that is sex trafficking and confirms the links to the legal industry.

"Nobody who saw this documentary and the tragic testimony of its victims could so easily dismiss action to curb this industry,” he said.