The Reserve Bank says a Newshub journalist leaked its interest rate decision last month ahead of schedule.
The bank said an investigation has shown a journalist with Newshub MediaWorks sent the decision to others in the media group from the pre-release briefing, who then contacted Michael Reddell, a former Reserve Bank of New Zealand official.
Governor of the Reserve Bank of New Zealand Graeme Wheeler said the leak was a "serious and disappointing" breach, which could have led to improper gain on financial markets.
The bank said it was scrapping its lock-ups for media and financial analysts, and would now hold news conferences after the statements have been released.
Mr Reddell said he had been told of the central bank's surprise decision to cut its official cash rate by a quarter percentage point to 2.25 percent about an hour before it was formally announced.
MediaWorks group chief executive Mark Weldon said MediaWorks apologises unreservedly to the Reserve Bank.
"Once MediaWorks was aware a leak had taken place, it conducted its own investigation to determine whether the leak had come from within MediaWorks and self-reported that to the Reserve Bank."
MediaWorks acting chief news officer Richard Sutherland said the leak was caused by a "failure within news to follow proper process".
Changes have been made and new policies and training would be implemented, he said, and they would address those responsible for the leak.
Prime Minister John Key said the Reserve Bank may consider reinstating locks-ups for interest rate reviews at some stage in the future.
Mr Key said the leak was disappointing, but the lock-ups did help financial markets gain a better understanding of the central bank's thinking.
"It's one of those things that maybe over time they might reflect on - I haven't had any discussions with them - but in the interest of reporting that is more accurate because they have had better information ahead of the embargo lifted, it has always been pretty useful to have a lock-up. Now, as I say, it is pretty disappointing that there has been a breach of that."