The Transport Accident Investigation Commission (TAIC) will no longer release "low profile" reports under embargo and is toughening rules for "high profile" reports.
Chief executive John Britton said the commission was looking for "more robust" ways of enforcing embargoes, such as a lock-in - where reporters are briefed in a closedroom - or legislative methods.
The move follows a front page story in the Sunday Star-Times which the commission believed deliberately breached an embargo.
The newspaper reported two days before an embargo was lifted last month that pilot error was to blame for the crash of a Piper Navajo Chieftain in June which killed pilot Michael Bannerman and seven Crop and Food staff.
The paper's editor, Cate Honore Brett, said a Wellington reporter had written the story independently of the embargoed report, which had been sent to Christchurch a few days earlier.
However, Mr Britton remains unconvinced, and said the commission had decided to stop releasing "low profile" reports under embargo, "at least for an interim period".
However, it would continue releasing "high profile" reports - judged by levels of media interest and loss of life - but under tough new embargo rules still being drawn up.
Mr Britton said the commission was considering several options and "talking to people with media knowledge".
He acknowledged that lock-ins were not popular with journalists.
"The point of what we're doing at the moment is to make the embargo process work better for everyone, and identify the various sound reasons for an embargo.
"It's beneficial for everybody to have an embargo process, and we have to try to steer a middle ground here."
An embargo was primarily to protect the family, next of kin, victims and others affected by reports.
It also allowed reporters time to review and analyse "complex technical detail" and attend commission briefings, he said.
However, the commission had no problem if journalists did independently source and publish information contained in embargoed reports, he said.
Mr Britton said the newspaper report had been the worst example of a breach in 10 years the commission had been releasing reports.
He said the commission had 10 years' experience to judge which reports were high or low profile, but would take into account the level of media interest in the accident.
The commission's only option now is to complain to the Press Council, which can order a newspaper to publish the findings.
