The BBC has apologised after its coverage of an FA Cup football match was marred by pornographic noises being played loudly while its presenters were live on air. Gary Lineker, the host, later said in a tweet that the moaning noises came from a hidden mobile phone which had been “taped to the back of the set” in the studio looking out over the pitch at Wolverhampton Wanderers’ Molineux stadium. The embarrassing incident occurred before kick-off in the third round replay fixture between Wolves and Liverpool on Tuesday night. As Lineker previewed the tie with pundits Paul Ince and Danny Murphy, the audible noises broke out in the background. The presenter looked momentarily startled by the prank and struggled to keep a straight face as he cut to colleague and fellow former England striker Alan Shearer in the commentary gantry. Lineker tried to laugh off the incident as the noise continued to blare out and said to Shearer: “Somebody’s sending something on someone’s phone, I think. I don’t know whether you heard it at home.” Minutes into the first half of the match, Lineker tweeted a photograph of the phone, commenting: “Well, we found this taped to the back of the set. As sabotage goes it was quite amusing.” A BBC spokesperson tweeted: “We apologise to any viewers offended during the live coverage of the football this evening. We are investigating how this happened.” Liverpool won 1-0, having scored the only goal of the game in the first half. During the half-time analysis, Lineker said to Ince and Murphy: “Harvey Elliott’s goal was a screamer … which was not the only one we’ve had tonight.” The stunt was picked up on by viewers as the incident was clipped and widely shared on social media. Daniel Jarvis, a self-styled YouTube prankster, claimed he was behind the stunt, posting a video on Twitter that seemed to show him at the TV studio at Molineux.