The Council for Civil Liberties says the National Party's plan to crack down on benefit fraud will cost more money than it saves.
National has announced it would introduce increased data-matching between government agencies to target those who abuse or exploit the welfare system, a move critics say is beneficiary bashing.
National says there were 690 benefit fraud prosecutions in 2010/2011 involving more than $22 million. A further $183 million was counted as overpayment because it fell below the prosecution threshold.
National party social development spokesperson Paula Bennett says increased data-matching will cost about $700,000 and save an estimated $200 million over four years.
Council for Civil Liberties chairman Batch Hales says that wasn't the case the last time this method was used - and it turned out that rather than people abusing the system, the system itself was to blame.
"Some of them had been trying to pay back this money which they kept on getting, and couldn't get it back," he said.
"Most people aren't trying to abuse the welfare system, most people are trying to get off welfare. This is beneficiary bashing."
National is also pledging to cancel benefits for people who refuse to apply for a job because they are asked to take a drug test, or who fail a pre-employment drug test.
Forest Owners Association senior policy analyst Glenn MacKie says some people have admitted they don't apply for jobs in the industry because they don't want to be drug tested - but others have told them that it has motivated them to give up drugs.
Drug Foundation executive director Ross Bell says he'd like to see more detail on the policy and a greater commitment in terms of funds for addiction treatment.
Beneficiaries who are on the run from the police, with a warrant out for their arrest, would also have their benefit stopped - or reduced by half if they are supporting children.