Ben Smith has opened up about his Olympic heartache, and why he chose the Highlanders over a bid for gold in Rio.

The World Cup winning fullback has backed All Blacks coach Steve Hansen, who rejects any claims that he coerced players such as Smith towards staying with 15s rather than pursuing a gold medal with the national sevens team.

Smith said the decision was entirely his own, but also difficult to make.

"I was in a tough position. I did want to have a go at the sevens but also wanted to be part of the Highlanders...it's a tough job to do both," Smith told Tony Veitch on Newstalk ZB.

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"It was a massive decision at the time - there are always going to be tough decisions so you just make it and get on with things. The Highlanders have worked really hard to get where we've got to and I want to continue on and be part of that. "

Smith said part of his decision involved wanting to have time with his family and get maximum rest rather than play the sevens tournaments in late January and early February.

Smith, who won a 2010 Commonwealth Games gold medal, said there were no guarantees he would even make the transition well enough to be picked for the Olympic sevens squad. And he didn't want to suit up for the Highlanders and then have to quit them come playoffs time.

"At the end of the day I wanted to be committed to one cause and to me that was the Highlanders - there was no pressure from anywhere else," he said.

"He (Steve Hansen) was really supportive of whatever I wanted to do. The (timing) was a bit niggly. I wanted to see it right through with the Highlanders."