The NSW Police stands accused of targeting poorer people by choosing not to test for substances preferred by wealthier sections of society such as cocaine.

The police, who are greatly increasing the use of roadside tests across NSW, test for only three types of drugs: cannabis; amphetamines and methamphetamine; and MDMA, the party drug known commonly as "ecstasy" or "molly".

A saliva swab being taken. Credit:Ken Irwin

But it can be revealed that Dräger, the German multinational that supplies police with roadside testing machines, boasts of its capability to detect cocaine and a range of other drugs not currently tested for in NSW.

The Greens' Justice spokesman, David Shoebridge, has accused the police of targeting drug users from certain social classes.