Richie McCaw

McCaw has only been on Facebook for a few weeks, after Carter finally convinced him to join the social media revolution in the wake of their World Cup final victory celebrations earlier this month.

The 34-year-old flanker played a world record 148 Tests, 131 of them wins, and led the All Blacks to two World Cup final victories, including last month's triumph against Australia.

McCaw is also a three-time winner of the World Player of the Year award.

The news, expected for some time, comes 24 hours after the death of iconic All Blacks winger Jonah Lomu.

McCaw, who turns 35 on 31 December, led the All Blacks to their third World Cup triumph two weeks ago when his side beat Australia 34-17 in the final at a packed Twickenham stadium in London.

The All Blacks were the first team to retain the trophy, after the openside flanker led the team to victory in 2011 while playing with a broken foot.

New Zealand Prime Minister says Richie McCaw will probably accept a knighthood when he decides to retire from his rugby career but he doesn't want to "embarrass" him by bringing it up.

John Key told TV3's Paul Henry show that he had yet to ask the All Blacks captain when he would retire.

"I don't want to put him in a position where he feels he has to say something to be. I don't want to put the guy on the spot," he said.