All Blacks captain Richie McCaw should watch his back - because Prime Minister John Key says he risks getting tasered if he fails to win the Rugby World Cup next year.

Mr Key this morning addressed an audience of Kiwi businessmen in South Korea's capital, Seoul.

Who has the most important job? All Blacks captain Richie McCaw (R) talks to New Zealand's Prime Minister John Key. Credit:Reuters

He joked he had given Mr McCaw the hard word about clinching the World Cup when New Zealand hosts the tournament next year.

"I've tried to tell Richie McCaw that it's very important - it's an election year," Key said.