A man has been charged with public mischief and could face up to 12 months in prison after an investigation into a listening advice found in the New Zealand rugby team's hotel ahead of a crunch match against Australia.

The bug was found by coaching staff at the All Blacks' Sydney base before a Bledisloe Cup test last August - a game they went on to win 42-8.

In response to the charges on Tuesday, head coach Steve Hansen said he found the incident "bizarre and unbelievable".

"It’s very hard to understand," he said in a statement. "The charged man has worked for the All Blacks, and many other organisations, for a long time and is someone who is trusted and well-respected by us."

New South Wales state police issued a statement saying the 51-year-old man would appear in a Sydney local court on March 21.

New Zealand management discovered the listening device on Monday, August 15, but reportedly didn't notify police for five days - with news emerging on the morning of the match.

At the time, New Zealand Rugby said a device similar to that used by law enforcement and spy agencies was found in a chair in the room which was being used for sensitive tactical and planning discussions.

The man charged has been identified as Adrian Gard, a director of the Brisbane-based security and investigations company Bodyguards International. The company has worked for the All Blacks in Australia for more than 10 years, and has had other high-profile clients including former US President Bill Clinton, Tiger Woods, and Oprah Winfrey.

The charges provided some closure in the case, Australian Rugby Union chief executive Bill Pulver said in a statement.

Lions Watch second instalment Show all 15 1 /15 Lions Watch second instalment Lions Watch second instalment 1. Jack McGrath EDINBURGH, SCOTLAND - FEBRUARY 04: Ireland player Jack McGrath in action during the RBS Six Nations match between Scotland and Ireland at Murrayfield Stadium on February 4, 2017 in Edinburgh, Scotland. (Photo by Stu Forster/Getty Images) Getty Images Lions Watch second instalment 2. Rory Best EDINBURGH, SCOTLAND - FEBRUARY 04: Ireland captain Rory Best carries the ball during the RBS Six Nations match between Scotland and Ireland at Murrayfield Stadium on February 4, 2017 in Edinburgh, Scotland. (Photo by Stu Forster/Getty Images) Lions Watch second instalment 3. Tadhg Furlong The third cog in an all-Irish front-row that posed Scotland all sorts of issues in their Murrayfield encounter. Carried well and frequently, giving forward momentum that allowed the Irish to attack from in the second half. Lions Watch second instalment 4. Jonny Gray Ireland's lock Devin Toner (L) vies with Scotland's lock Jonny Gray during the Six Nations international rugby union match between Scotland and Ireland at Murrayfield in Edinburgh, Scotland on Febuary 4, 2017. / AFP / Paul ELLIS (Photo credit should read PAUL ELLIS/AFP/Getty Images) AFP/Getty Images Lions Watch second instalment 5. Alun Wyn Jones Wales' lock Alun Wyn Jones (R) runs with the ball during the Six Nations international rugby union match Italys vs Wales on February 5, 2017 at the Stadio Olimpico in Rome. / AFP / Alberto PIZZOLI (Photo credit should read ALBERTO PIZZOLI/AFP/Getty Images) AFP/Getty Images Lions Watch second instalment 6. Maro Itoje England's flanker Maro Itoje claims the ball in the line-out during the Six Nations international rugby union match between England and France at Twickenham stadium in southwest London on February 4, 2017. / AFP / Ben STANSALL (Photo credit should read BEN STANSALL/AFP/Getty Images) AFP/Getty Images Lions Watch second instalment 7. Justin Tipuric ROME, ITALY - FEBRUARY 05: Justin Tipuric of Wales charges towards Maxime Mbanda of Italy during the RBS Six Nations match between Italy and Wales at the Stadio Olimpico on February 5, 2017 in Rome, Italy. (Photo by David Rogers/Getty Images) Getty Images Lions Watch second instalment 8. Billy Vunipola Eddie Jones will be without Billy Vunipola for this year's Six Nations competition Getty Lions Watch second instalment 9. Greig Laidlaw EDINBURGH, SCOTLAND - FEBRUARY 04: Scotland captain Greig Laidlaw in action during the RBS Six Nations match between Scotland and Ireland at Murrayfield Stadium on February 4, 2017 in Edinburgh, Scotland. (Photo by Stu Forster/Getty Images) Getty Lions Watch second instalment 10. Owen Farrell LONDON, ENGLAND - FEBRUARY 04: Owen Farrell of England makes a break during the RBS Six Nations match between England and France at Twickenham Stadium on February 4, 2017 in London, England. (Photo by Shaun Botterill/Getty Images) Getty Images Lions Watch second instalment 11. Elliot Daly LONDON, ENGLAND - FEBRUARY 04: Elliot Daly of England grounds the ball to score a disallowed try as he is forced into touch during the RBS Six Nations match between England and France at Twickenham Stadium on February 4, 2017 in London, England. (Photo by Shaun Botterill/Getty Images) Getty Images Lions Watch second instalment 12. Robbie Henshaw Robbie Henshaw is a contender to start for the Lions Getty Lions Watch second instalment 13. Jonathan Davies ROME, ITALY - FEBRUARY 05: Jonathan Davies of Wales slides over to score his team's first try during the RBS Six Nations match between Italy and Wales at the Stadio Olimpico on February 5, 2017 in Rome, Italy. (Photo by David Rogers/Getty Images) Getty Images Lions Watch second instalment 14. George North ROME, ITALY - FEBRUARY 05: George North of Wales evades the attempted tackle from Leonardo Ghiraldini of Italy enroute to scoring his team's third try during the RBS Six Nations match between Italy and Wales at the Stadio Olimpico on February 5, 2017 in Rome, Italy. (Photo by David Rogers/Getty Images) Getty Images Lions Watch second instalment 15. Stuart Hogg EDINBURGH, SCOTLAND - FEBRUARY 04: Stuart Hogg of Scotland is tackled by Keith Earls of Ireland during the RBS 6 Nations match between Scotland and Ireland at Murrayfield Stadium on February 4, 2017 in Edinburgh, Scotland. (Photo by Ian MacNicol/Getty Images) Getty Images

"The ARU and the Wallabies were never accused of any wrongdoing, however, it was still important that this matter reached a conclusion to provide complete reassurance to all fans that the organisation and the team had no part in any of this," Pulver said.

"There may be some questions that remain but certainly today's news is welcome news that an individual has been called to account over this incident."