Sky Sports have been forced to apologise to their viewers after ex-referee Dermot Gallagher used the term "Holocaust" during an analysis of Celtic's Champions League first-leg defeat to Juventus.

Gallagher, who regularly appears on Sky Sports News to discuss recent refereeing issues, was asked why the linesman had failed to see that Alessandro Matri's initial shot had crossed the line during last night's 3-0 defeat to Juve.

Gallagher said on air: "The problem for me is I don't think there is any tangible evidence that they do anything.

"But for a Juventus player following up a shot very, very quickly we could have had another Holocaust last night. I am convinced that the assistant and the guy on the goal line don't know the ball is in."

Presenters Rob Wooton and Hayley McQueen swiftly apologised for the remark while Sky Sports released a statement saying: "Dermot Gallagher made a comment on air that he clearly now regrets. We have apologised on behalf of him and Sky Sports for any offence caused."

Gallagher was criticised by viewers on social network site Twitter.