All Black Charles Piutau is holding on to his Rugby World Cup dream after confirming his decision to head to Northern Ireland at the middle of next year.

The 23-year-old Blues back has signed for Ulster on a two-year deal beginning in July 2016.

Piutau, who has 14 caps, says he remains passionate about playing for the All Blacks and making the squad to defend the World Cup.

“I’ll put my best foot forward to wear a black jersey at the end of the year,” he said on Thursday.

As to whether his decision to head offshore would affect his chances, he said: “I’m not sure. It’s out of my hands.”

All Blacks coach Steve Hansen has expressed disappointment at Piutau’s decision not to re-sign with New Zealand Rugby.

Piutau said he was faced with a tough choice.

It boiled down to having two contract options in front of him and he took the advice of family, friends, church people and others in his support team.

The clincher was the prospect of being out of his comfort zone and living in a new country, experiencing a new culture and playing a different type of rugby.

The money on offer from Ulster and the ability that gave him to support his family was also a big factor.

He declined to say how close he was to re-signing with the NZR, describing it as a personal matter.

Piutau made his Test debut against France in 2013 and last played for the All Blacks against Wales last November.

Blues chief executive Michael Redman said the franchise hoped Piutau could be part of their Super Rugby campaign next year before he headed to Ulster, but that decision was up to NZR.

Redman also said the Blues would keep the door open for Piutau at the end of his stint overseas.