RTÉ pundit Eamon Dunphy has apologised for letting the 'F' word slip live on air during commentary of last night's Brazil vs Mexico World Cup game.

Speaking to RTÉ TEN, he said: "I thought we were on an ad break. I used the 'f' word and it's not right. I am very conscious that kids were watching and you can't normalise that kind of language as we are broadcasters."

Fellow commentator Didi Hamann was also unaware they were back on air as he could be seen checking his phone. 

Dunphy added: "I reflected on it and it was obviously wrong, although in the great scheme of things I didn't libel or defame anyone. There were no callers complaining and people on social media were generally sympathetic. I think they realised it was a mistake."

The World Cup coverage starts today at 4:30pm, RTÉ Two, with Australia vs Netherlands.