A report which found the country's health and safety regulator lacks a clear strategy and cannot say if it is effective is "shocking", the National Party says.
The independent review , commissioned after WorkSafe complained it was underfunded, found it could not "clearly describe its role", was not acting on known instances of harm, and had not implemented recommendations previously made in prior reviews.
"It's quite shocking," said National Party workplace relations and safety spokesperson Paul Goldsmith.
"WorkSafe doesn't seem to have a clear focus on its objectives and is unable to show that they're making progress towards those objectives. And that's pretty basic stuff for any agency."
It was also concerning that the review could not say whether WorkSafe's activities were effective, Goldsmith said.
"This is an agency that has seen a 50 percent increase in its budget since this government took office. Once again, we see a government that knows how to pour more money in, but not how to get better outcomes."
Goldsmith called on Workplace Relations and Safety Minister Michael Wood to ensure the agency had a "clear understanding of what it's going to achieve."
"I'm just asking the minister to do his basic job. It's 101 when it comes to ministerial oversight and responsibility."
WorkSafe said it would implement all 20 recommendations made in the review.
Otago University law lecturer Simon Connell, who researched accident law, said the review's findings were "concerning."
"WorkSafe seems to have the best of intentions. They're trying to innovate, they're trying to respond to developments as they occur, but they are not always doing it in a clear strategic, disciplined way."
WorkSafe's focus on taking enforcement actions higher up the supply chain - which the review said may not be the most effective use of its resources - could prove problematic for WorkSafe's prosecutions relating to the Whakaari eruption, Connell said.
"I note that the dismissal of the prosecution against NEMA [National Emergency Managemen Agency] suggests they were really trying to reach too far upstream.
"The other issue that comes up in relation to looking upstream, is that becomes awkward for WorkSafe, because if you go far enough upstream you find WorkSafe."
While it was clear WorkSafe had a mission to become a world class health and safety regulator, "it was clear they're still not there yet," Connell said.
Workplace Relations and Safety Minister Michael Wood did not respond to requests for comment.