All Blacks' Sam Whitelock commits to Crusaders, New Zealand

(Photo by Phil Walter/Getty Images)

Double Rugby World Cup winner Sam Whitelock has added three more seasons to his contract with New Zealand Rugby and the Crusaders.

The durable lock joins Ben Smith in signing a deal through to 2020, a year beyond the next World Cup in Japan.

All Blacks coach Steve Hansen says having Whitelock's services locked in place is a major boost for the national side after the announcement of the British & Irish Lions tour squad to visit New Zealand this season.

Whitelock is a key member of the All Blacks' leadership group, having formed one of the best locking partnerships in world rugby alongside Brodie Retallick.

"Having him secured until 2020 is massive," Hansen said at Crusaders training on Thursday.

"He slips under the radar a bit, but his performances are very, very consistent and very, very high.

"He's highly skilled. Not only can he do his basic stuff in the lineout and scrum and breakdown, but he's a good ball carrier, and a good distributor.

"He's a pretty unique player."

Whitelock, 28, didn't wait long to sign when his contract came up for renewal.

"When I considered whether my immediate playing future was here in New Zealand and Christchurch, I didn't need to look far for the answer," Whitelock said.