Ma'a Nonu has signed with the Highlanders.

The All Blacks midfielder this afternoon confirmed he will leave the Blues after just one season and join All Blacks team-mates such as Andrew Hore, Tony Woodcock, Aaron Smith and Hosea Gear at the Dunedin-based franchise.

Former All Blacks lock Brad Thorn is also in the process of signing with the team that is coached by Jamie Joseph.

Nonu, who has played under Joseph with Wellington, said the major reason for signing with the Highlanders was because it was the "best decision'' for his family.

He said the "finer details'' are being worked out by his manager, the New Zealand Rugby Union and the Highlanders.

Nonu's decision to leave the Blues will not thrill new coach John Kirwan who hoped to build his backline around the big second five-eighth.

"Just on the Blues, I really respect 'JK' and I wish him all the best but right now I think this is the best decision for me and my family,'' Nonu said.

Nonu said he spoke Kirwan last week.

"As I said before it has got nothing to do with the Blues. It is a decision I have made for myself and my family.''

Although it was understood Nonu had signed with the Blues for next season, he appears to have an exit clause that allowed him to join the Highlanders.

When quizzed on this, he stated: "You will have to ask the manager about the contract system mate. I just play footy.''

Speaking in the foyer of the All Blacks hotel in Christchurch, where they are based before flying to Brisbane on Thursday, Nonu fielded just a few questions before exiting the media scrum.

The informal press conference lasted less than two minutes before he politely terminated it.

His declaration to remain in New Zealand is good news for All Blacks coach Steve Hansen who will have been left with a gaping hole in his backline after Sonny Bill Williams defected to Japan earlier this year.