SYDNEY (AFP) - Australia imposed an interim ban on 19 synthetic cannabis and cocaine-like drugs on Sunday as part of a crackdown on the psychoactive substances that mimic the highs of their illegal counterparts.

Assistant Treasurer David Bradbury said the 19 products will be banned from sale and supply for up to 120 days under consumer laws, a measure which will give states and territories time to update their laws to ban them.

"Synthetic drugs are dangerous substances that can kill and should not be available for sale," Mr Bradbury said.

Many synthetic drugs are already banned in parts of Australia, but Mr Bradbury said the market is fast-moving and suppliers have shown a willingness to change brand names and packaging to get around bans made under consumer laws.

Australia's most populous state New South Wales temporarily banned synthetic drugs earlier this month after a 17-year-old Sydney boy fell to his death after taking a synthetic LSD product that made him believe he could fly.

Home Affairs Minister Jason Clare confirmed on Sunday that the government will also develop legislation to ensure unauthorised synthetic drugs cannot be imported. The move will mean that "new drugs coming onto the market are presumed to be illegal until the authorities know what they are and clear them as safe and legal".

Mr Clare said a range of synthetic drugs were being sold in Australia, including via the Internet. They mimicked the effects of cannabis, cocaine and methamphetamine and were being marketed as a legal alternative to illicit drugs. He said the new legislation will be in line with that already in place in Ireland and due to be brought into force in New Zealand in August.

Last month, Europe's drug agency said 73 new psychoactive substances were detected on the market last year - compared to just 49 in 2011 - and a greater proportion were from more obscure chemical groups.