Outside back Charles Piutau, the All Black who signed to play for Ulster next season, will miss the rest of the Super Rugby season after being injured over the weekend, his side the Auckland Blues have said.

Piutau and fellow All Black, loose forward Jerome Kaino will miss the rest of the season, the Blues said on Monday. Piutau sustained a medial ligament injury to his knee that will put him out of action for six weeks.

The 23-year-old hopes to force his way into the All Blacks squad before his move to Ulster for next season, but the injury will come as a major setback.

Kaino will be sidelined for eight weeks after suffering a compound fracture to the ring finger of his left hand.

The injury to Kaino, who started every match in the World Cup on home soil four years ago and played eight tests at blindside flanker for the All Blacks last season, will be a blow to New Zealand coach Steve Hansen.

A nominee for World Player of the Year in 2011 and key member of Hansen's squad, the physical back row forward is now a major doubt for the All Blacks' season-opener against Samoa in Apia on 8 July.

New Zealand then play Rugby Championship tests against Argentina in Christchurch on 17 July and South Africa in Johannesburg on 25 July before back-to-back matches against Australia in Sydney and Auckland on 8 and 15 August.

The All Blacks’ World Cup defence begins against Argentina at Wembley Stadium in London on 20 September.

There are also concerns about in-form Wellington Hurricanes out-half Beauden Barrett, who injured his knee on Saturday and will have scans on the joint later on Monday.

With Aaron Cruden sidelined for six months with a knee problem of his own, New Zealand can barely afford to lose another out-half.