Government figures show beneficiaries have failed only 466 pre-employment drug tests in the past three years.
Tens of thousands of beneficiaries are tested each year.
Prime Minister Bill English said yesterday he heard from employers two or three times a week who struggled to find enough New Zealanders to fill job vacancies - in many cases because the applicants failed the drug test.
"One of the hurdles these days is just passing the drug test ... Under workplace safety, you can't have people on your premises under the influence of drugs and a lot of our younger people can't pass that test."
His comments were based on anecdotal evidence, Mr English said.
He said the more than 42,000 migrants who came to New Zealand on work visas in the year to January 2017 would not fill the skills gap.
The Ministry of Social Development said the 466 included those who failed and those who refused to take the test.
Some failed more than once.
The ministry did not have the total figure for how many tests were done over the three years, but said there were 32,000 pre-employment drug tests in 2015.
Today, Mr English denied he was scapegoating a few drug users to take attention off record immigration and those workers taking jobs here.
When asked by reporters, he would not name the companies he said told him they could not hire New Zealanders because they failed drug tests.
Drug Foundation executive director Ross Bell said Mr English was behaving irresponsibly in scapegoating young New Zealanders.
"And in this case we're picking young New Zealanders who are sitting on their couch, who are high all the time, lazy stoners, and I actually think it is a message that might appeal to some people.
"It's not a message that is true, and I think it's dangerous ground for a prime minister to be on."
Mr Bell said Mr English's comments were nothing more than dog-whistle politics in an election year.
"What I described was the presence of a problem," Mr English said.
"These are people who turn up with drug-taking habits, and some of them are young.
"The assertion that, somehow, this doesn't exist, is unrealistic."
Give them a couple of weeks to clean up'
Labour Party leader Andrew Little told Morning Report today that employers, such as horticultural growers in Hawke's Bay, had told him they wanted Work and Income to give young people two weeks' preparation for getting into work.
"If they test positive at the beginning of the two weeks, give them a couple of weeks to clean up and get it out of their system," he said.
Last year, then-prime-minister John Key said he continually heard from employers frustrated with New Zealanders' work ethic and drug problems.