The International Rugby Board (IRB) has waded into the Brian O'Driscoll tackle debate, with chairman Syd Millar believing the sport is more dangerous now that teams are bending the law at clean outs.

Millar said the injury suffered by Lions captain O'Driscoll when he was cleaned out at a ruck by All Blacks Tana Umaga and Keven Mealamu in the first Test on Saturday has only served to highlight a serious problem.

"That tackle was made when the ball was gone and that's been happening," Millar said.

"It's not part of rugby to be taking people out off the ball. It's dangerous, the guy's not expecting, it shouldn't be part of rugby."

Millar said teams were now training to take players out further off the ball than the law allowed but were getting away with it because of lax interpretation by referees.