Labour Minister Simon Bridges says prosecutions are "very likely" for forestry owners who have breached safety standards.
Up to 150 forestry businesses have been inspected by officials to check their compliance with health and safety rules, and 14 have been shut down.
Mr Bridges told reporters this morning: "My understanding is that there is one prosecution pending, there are other investigations ... What I certainly can say is there is the likelihood of prosecutions in this industry."
He added: "We are warning the industry that they need to get their house in order. We're stepping up, we're resourcing this, doing the inspections, changing the law. We need them to take that seriously and also step up. Because if they don't, there will be consequences."
The Ministry of Business, Innovation and Employment was handling the prosecution but would soon hand it over to Worksafe New Zealand, a newly formed regulatory body.
The minister could not comment on whether the prosecution related to any of the nine deaths in the industry this year - two of them last week.
Under the Health and Safety Act, managers or directors could face up to two years' jail if the company was found to have acted recklessly. Proposed law changes would increase the penalty for reckless behaviour to a maximum of five years' jail.
Mr Bridges said the high death rate in the industry was unacceptable.
"Every single death is a tragedy. We've had an appalling record for a very long time."
He said further law changes would make forest owners responsible for safety throughout their entire supply chain. These changes would be introduced in a bill early next year.
The Ministry of Justice was investigating whether corporate manslaughter charges could be introduced in New Zealand.
The ministry was considering the possibility of a manslaughter charge against corporations, which was already in place Britain or Australia.
An Independent Task Force on Health and Safety said earlier this year that a manslaughter charge against independent directors was unworkable.
Prime Minister John Key said yesterday that a corporate manslaughter charge was "off the table" but clarified this morning that no final decision had been made.
He said: "There is a general belief that it hadn't been successful in the UK and had been very difficult to take prosecutions," he told 3News.
Labour leader David Cunliffe said his party supported the introduction of a charge which targeted individual directors or senior executives.
"The advice that we've received is that it is a worthwhile addition to the legal framework ... and it provides a strong incentive for good behaviour for directors and boards.
"When matters are life and death, it's not sufficient for directors and boards simply to be able to get away with a financial penalty."