Welfare lobby groups are worried a new initiative to randomly drug test job hunters demonises them.
From next year, 5000 Newstart and Youth Allowance recipients across three locations will be roped into two-year testing trials, with those who test positive to have their payments quarantined.
"This is further demonising of people on social security, people on the lowest incomes in the country," Australian Council of Social Service chief Cassandra Goldie told ABC TV on Wednesday.
Prime Minister Malcolm Turnbull defended the measure, saying there was a correlation between drug addiction and unemployment.
"I am really disappointed by the criticism of that - I would have thought more people wouldn't say should have done it years ago," he told ABC TV.
"We want to get people off welfare into employment. This is one of the many ways we seek to do that."
He said random drug testing was common in many industries.
Jacqui Lambie said she liked the look of the policy, which she had been calling for since entering the Senate, but wanted to see the detail.
"I need to know what areas they're going to roll it out in and how it will be conducted," she told ABC TV.
"By second-guessing which ones they're going to do rather than doing it full-on random, I'm not sure they'll get the result they want to achieve."