Hansen: Quotas is Coetzee's biggest challenge

Hansen, who forged a close friendship with Coetzee's predecessor Heyneke Meyer, said he rated the newcomer's ability as a coach.

"I rated the last bloke [Meyer] too, but it's a very tough environment that they're operating in over there," he told Radio Sport.

"That environment hasn't changed, so it'll be just as tough for [Coetzee]. He's a good coach, he deserves to be there."

Coetzee's main challenge at the helm of the two-time world champions is to field a team at the 2019 World Cup in Japan that is 50 percent black.

Hansen, who guided the All Blacks World Cup glory last year, said every national coach's role involved politics, but the situation in South Africa was unique.

"What is different for him is that they've got a quota system and sometimes I think that means they're not picking the best players they can," he said.

"It makes it tough, but that's the way it is in that country and you go in knowing that. I'm sure he'll deal with that really well.

"South Africa have always been strong and I don't see it being any different."

Hansen said the Springboks' quota system was difficult for New Zealanders to understand but he respected that it was part of the country's way of dealing with its apartheid past.

"It's hard for us to wrap our heads around, but we didn't live in that country and it's history," he said.

"That history is still playing itself out and it's not for us to bag [criticise] them."

However, he said that anything other than merit-based selection risked undermining a team's confidence and performance.

"At the end of the day, one thing I do know is that your sporting teams have got to be selected on merit because if they're not people start questioning whether they should or shouldn't be in the team," he said.

"What that does is it affects your confidence and the golden rule is that if you've got a team that's confident, they'll play well, no matter who they are."

New Zealand play South Africa in the Rugby Championship in Christchurch on September 17, with the return fixture in Durban on October 8.

List of post-isolation South Africa national rugby coaches:

1992: John Williams

1993: Gerrie Sonnekus

1993: Ian McIntosh

1994: Kitch Christie

1996: Andre Markgraaff

1997: Carel du Plessis

1997: Nick Mallett

2000: Harry Viljoen

2002: Rudolf Straeuli

2004: Jake White

2008: Peter de Villiers

2012: Heyneke Meyer

2016: Allister Coetzee

Agence France-Presse