New Zealand Rugby chief executive Steve Tew said it was likely to have recorded a team meeting.
The revelation sent shockwaves around the rugby world and is likely to force an investigation by the governing body. World Rugby declined to comment last night.
After last night's Bledisloe match, attention will today turn to who planted it. Hodder said police had no theories. The hotel is also investigating how it happened.
Australian Rugby Union chief Bill Pulver told the Herald on Sunday the ARU had no involvement in the scandal and both unions had handed the incident over to police.
He was concerned it had come to light "on match day".
Former coach Sir Graham Henry told the Herald on Sunday he was shocked. However, he said there had been spying in the past with videoing of training or taking notes.
"That sort of thing has happened in world rugby before, let's be frank about that. But I've never heard of bugging before."
He revealed All Black management had employed security advisors to check for breaches - including listening devices - since at least 2004.
All Black great Sir John Kirwan described it as a "sad day for rugby".
"It's really important we get to the bottom of who did it and make sure that they're punished accordingly. It's bringing the game into disrepute."