New Zealand captain Ryan Nelsen listens to the national anthem before a game against Belarus at the 2012 London Olympics.

All Whites great Ryan Nelsen is urging New Zealand Football to take their fight against Olympic Games expulsion to the highest court of appeal.

New Zealand Football (NZF) confirmed on Monday they would appeal against their disqualification from the Oceania Olympic qualifying tournament in Port Moresby after defender Deklan Wynne was declared ineligible.

Nelsen, who captained New Zealand at the 2008 and 2012 Olympic Games tournaments, said NZF have "a duty of care to the players", who would be "shattered" at the scuppering of their Olympic dream.

"It's devastating for the players, and not just for soccer. It's devastating for New Zealand sport, who won't have another Olympic team to follow.

"For me, as a fan of New Zealand sport, you always want to watch New Zealand teams play at the Olympics. Whether it's hockey or soccer, it doesn't matter."

Nelsen said it was disappointing that an administrative error had proved costly, but NZF may have thought Wynne was eligible because he had played for the All Whites and at the Fifa under-20 world championships.

"But rules are rules. That's why you pay for good lawyers, and good administrators [to ensure the right decision are made]."

Nelsen, who played in the English Premier League for eight years and captained the All Whites at the 2010 World Cup finals in South Africa, said his heart went out to the young New Zealand players, who had had "one foot on the plane to Rio."

The impact of the expulsion could be "career-changing" because the Olympics were a great shop window.

"There are so many scouts [from major football clubs] there. The whole world watches the Olympics; it's a significant stepping stone [for young players]; it's a real shame."

Nelsen said NZF now had "a duty to the players to take this [appeal] as far as they possibly can."

"The players did exactly what they were asked to do [on the field], in difficult circumstances as well. There's now a duty of care for New Zealand Football and the New Zealand Olympic Committee to take it as far as they can."

NZF had to be prepared "to pay to get the right legal team to see it through."

While Nelsen felt it might be difficult to get Fifa to overturn the Oceania confederation's decision, the Court of Arbitration for Sport could be an ultimate avenue.

Nelsen said playing at the Beijing and London Olympics were memorable moments in his own career.

"Ninety-nine per cent of all sports people in the world would want to play at events like the Olympics and football World Cup finals."

He felt "so lucky" to have played in both.

Nelsen said it was not only the Oly Whites, the current New Zealand Olympic under-23 squad, who would be gutted at the door to Rio being slammed shut.

The Olympics is primarily for players aged under 23, but each nation is permitted three over-age players.

Nelsen suspected All Whites captain and West Ham United EPL defender Winston Reid would also be disappointed at being denied a chance to play at Rio.

Meanwhile, Nelsen, 37, confirmed he has no plans to return to football coaching or management after being sacked as head coach of the Toronto FC Major League Soccer club in 2014.

He is now focusing full-time on his business interests and is about to move his family from Toronto to Washington DC, where he played for DC United from 2001 to 2005.

Nelsen said he enjoyed his 18-month stint at Toronto FC. Working alongside the "upper echelons" of the club's executive management had been a "great learning experience".

But he had "ticked the coaching box" now and saw his future in the business arena, where he is working on a number of private projects.

But he was following football "even more now" and was enjoying watching the game, as a fan, for the first time in 20 years.

Nelsen travels to England "every three to four months" on business and regularly catches up with Reid at West Ham.

He said his successor as All Whites captain was "a role model for any aspiring sports person in New Zealand" for the way he had "worked hard through some tough times" at the London club to establish himself "among the top 15 defenders in the Premier League".