New Zealand bosses continues to harbour concern about the readiness of Japan’s inaugural entry into Super Rugby.

Next year’s competition has been expanded to 18 teams, featuring entries from Japan and Argentina and a sixth entry from South Africa, the Port Elizabeth-based Kings.

NZ Rugby chief executive Steve Tew says while Argentina looks set to provide a strong and well-organised franchise, he is worried about the state of Japan’s entry, the Sunwolves.

His concerns follow a meeting of Sanzar bosses in Sydney this week in which a Sunwolves representative outlined a lack of progress ahead of a start date in late February.

“They have not announced a coach yet so that is clearly an issue and they have not got a playing roster completely full so they are the two issues they have to put their foot on the throttle for,” Tew said.

“We are concerned about any expansion when you bring new teams into a competition and it takes a bit of time for it to bed down.

“On the upside it looks like the Argentinian side will be in very, very good shape. They’ve got a very strong playing roster and they might actually be a considerable worry.”

The Sunwolves, Kings and Argentina will all play in the eight-team South African Group while five teams each from New Zealand and Australia will contest the Australasian Group.

Tew reacted cautiously to recent comments from World Rugby chairman Bernard Lapasset, who said Japan would ideally be added to the four-nation Rugby Championship following their bright World Cup showing.

Tew says the concept of Japan joining New Zealand, Australia, South Africa and Argentina in the annual tournament remains on a list of long-term objectives.

“We are all very excited by what Japan achieved at Rugby World Cup but we remain pretty nervous about their readiness for Super Rugby and that is their next step forward.”