Wellington:Former All Blacks captain Tana Umaga has unleashed built-up frustration at southern hemisphere rugby referees as he took a further step towards retirement with his last Super 14 match.

"I think referees in this part of the world are lacking," Umaga said Saturday night after his Wellington Hurricanes were beaten 14-38 by the New South Wales Waratahs.

"Unfortunately referees in the northern hemisphere are better, which is sad to see," he said.

Umaga risked censure and a fine for breaching protocol by criticising the officials, but said he was speaking out now as he had only a domestic season to complete.

The 33-year-old, who has played more than 300 first class games including 21 Tests and 122 Super games, said it was not healthy to have players muzzled for fear of upsetting sponsors and employers.
 
"I'm lucky I have a Mastercard and Visa," he joked, referring to an All Blacks sponsor and rival.

"I believe I'm at a stage that I can speak out and I can take the (financial fine) if it comes," he said.

His criticism comes at time when there is more confusion than ever with the game's complicated laws and interpretations by referees, and Umaga said several laws needed changing and simplifying.

"Northern hemisphere referees have a better empathy for the game up there and something needs to be done," Umaga said.

"Apart from Jonathan Kaplan everyone is struggling and New Zealand and Australian referees are struggling," he said.

Umaga said referees should also be more accountable and face the media to explain their decisions.

"It's got to a stage where I want to tell my son to ref because it's the safest job going around and they get paid a lot," he said.