Irish referee Bertie Smith has pleaded innocence after an amazing yellow card bungle during Saturday's Allied Dunbar Premiership rugby union clash between Bath and Wasps.

Smith astonished players, coaches and an 8,000-strong crowd at the Recreation Ground when he cautioned Bath lock Martin Haag and Wasps flanker Paul Volley following a second minute dust-up.

The Cork official was completely unaware that English Rugby Football Union chiefs had scrapped yellow cards in favour of a sin-bin system this season.

"I didn't know anything about it until my touch judge told me 10 minutes into the game," said Smith. "I was appointed for this match a week or so ago but no-one said anything to me about yellow cards no longer being used."

Wasps director of rugby Nigel Melville said an English referee should have been given the game. "We spend all summer talking about refereeing and then we get an Irish official who doesn't know what is going on. As far as I am aware, there are no yellow cards any more," he said.