Opposition leader Simon Bridges has apologised to those affected by meth contamination evictions and clean-ups, but says he didn't know the tests weren't fit for purpose.
Last week, the government's chief science advisor Sir Peter Gluckman said there's never been evidence of illness from third-hand exposure to methamphetamine anywhere in the world.
Mr Bridges told Morning Report that it was an "incredibly frustrating" situation.
"I'm sorry that the advice we got was wrong and has made this situation what it is," he said.
"We got the wrong advice, we're not technical experts, we thought we were asking the hard questions."
When asked if he thought tenants who were evicted should receive compensation, Mr Bridges said: "My instinct is no, because ultimately agencies were following the rules at the time…
"I'm sure Phil Twyford will get advice on it, if the rationale is strong, let's see that," he said.
Mr Bridges said he didn't know the tests were not fit for purpose. However, in 2016 Bill English acknowledged that the tests were not fit for purpose.
Mr English, who was Housing New Zealand Minister at the time, said Housing New Zealand had said the tests weren't fit for purpose.
"They're operating to a Ministry of Health guideline which is internationally standard but it's regarded as not quite appropriate for dealing with use of P in houses," he said.