Marshall captained the Barbarians against New Zealand recently

The 31-year-old has a release clause in his New Zealand contract which allows him to move after the 2005 Lions tour.

"It is a really exciting challenge and something new for me," Marshall told BBC Sport.

Leeds rugby director Phil Davies added: "Justin is a world class player who will add greatly to this group with his professionalism on and off the field."

Marshall is the most capped New Zealand back of all time with 77 Tests behind him, but was left at home for the All Blacks' European tour in November.

MARSHALL FACTFILE NZ Test debut - 1995 v SA 77 caps, 24 tries Three Tri-Nations titles Four Super 12 titles

He did travel to England to captain the Barbarians against his international team-mates at Twickenham, and is intent on reclaiming his Test spot ahead of the Lions' visit in June.

"I am committed to New Zealand rugby this season," he added. "I enjoy a good challenge and it would be great to face the Lions."

Marshall is preparing to start training with the Canterbury Crusaders, whom he has helped to four Super 12 titles, on Monday ahead of the new season.

His intended departure later this year comes with the blessing of All Blacks coach Graham Henry.

It's an opportunity to step out of the comfort zone Justin Marshall

"I fully understand why Justin is making the change at this stage of his career," Henry said.

"While we never like losing world-class players from our ranks, there is no doubting that he has served New Zealand rugby well over a long period of time."

Marshall made his All Blacks debut in 1995, played in the 1999 and 2003 World Cups and captained the side on their 1997 tour of Britain.

"When I look back over the last 10 years of my playing career in New Zealand I feel incredibly satisfied at all I have experienced and achieved," he added.

"As a kid my dream was to one day wear the All Black jersey. To have been fortunate enough to wear the number nine jersey throughout the last 10 years has certainly been an honour and given me memories I will never forget.

He is one of those guys who always gives 100% - a great addition for the club and the Premiership From T

"I have relished the competitive environment in New Zealand at all levels of the game and I have great pride in our country and my province Canterbury.

"I will miss my many friendships with team-mates in various teams but know they will long continue in my life.

"Leeds will present new challenges. It's exciting to have the opportunity to set new goals, and compete in a different competition.