All Black captain Richie McCaw has turned down an invitation to attend Prince William's wedding next month because he wants to focus on his Super 15 comeback and the Rugby World Cup.

McCaw was surprised to receive the gold-embossed invitation to the prince's wedding to Kate Middleton at Westminster Abbey, but has declined to attend - a move, he says, which has horrified his female friends.

"I did get an invitation, it was a heck of an honour and I felt a bit lucky," he revealed yesterday.

He said he needed to concentrate on his recovery from foot surgery and get back to playing for the Crusaders in the Super 15.

"Had I still been injured and it had not been a World Cup year, then I'm sure things would have been different."

About 1900 guests, including New Zealand Prime Minister John Key and Governor General Sir Anand Satyanand, have been invited to the April 29 wedding.

Sporting stars including the former England football captain David Beckham, and Ireland's rugby skipper Brian O'Driscoll are also on the guest list.

"I was surprised to get an invitation, to be honest, though I have met William a few times," McCaw said.

The prince played rugby as a university student and is vice-patron of the Welsh Rugby Union.

Former Welsh captain Gareth Thomas is going to the wedding.

McCaw said he was several weeks away from top rugby, but was stepping up his training for his 104th Super cap.