UPDATED 9.14AM: Prime Minister Bill English believes one of the reasons New Zealand companies rely on migrants as workers is because Kiwis can't pass drug tests.

LISTEN ABOVE: Horticulture New Zealand chief executive Mike Chapman spoke to Rachel Smalley

English made the comments while discussing the country's record migration figures for the year to January.

He said he's heard anecdotal evidence from all industries, at least two to three times a week, that when companies open for applications, people turn up and it's hard to get someone to pass a drugs test.

The Horticulture sector agrees with the Prime Minister's comments about drug use preventing many Kiwis from getting jobs.

Horticulture New Zealand chief executive Mike Chapman said the organisation has a screening process with many of the schemes it runs.

He told Rachel Smalley it asks if people take drugs and whether they'd be prepared to give them up.

"Often the answer is 'no, this is my lifestyle, I will not give up taking drugs'. And the reason we have to be so careful around this is these workers are working around machinery."

Mr Chapman said their safety and the safety of other workers is at risk.

But Labour's immigration and workplace relations spokesperson Ian Lees-Galloway said it's likely Mr English is making this up.

"I think this is a case of Bill English repeating his view that young Kiwis are pretty damn hopeless and that he would rather employers be able to use migrants than be able to use New Zealanders."

Lees-Galloway said if the Government was genuine in supporting Kiwis to get work-ready, he wouldn't be touting anecdotal evidence.

"Bill English is in the business of blaming Kiwi workers rather than coming up with policy solutions that work for ordinary New Zealanders."