BBC station Radio 5 Live has been criticised by the broadcasting watchdog for letting the US band Rage Against The Machine swear four times on the breakfast show before they were faded out by a producer.
The rock group were interviewed in a live link from the US in December as their song, Killing In The Name, raced to number one in the UK charts backed by a Facebook campaign to stop X Factor victor Joe McElderry clinching the Christmas top spot.
After the interview, frontman Zack de la Rocha sang the lyrics "F*** you, I won't do what you tell me" four times while performing Killing In The Name before the track was faded out by the show's producers.
Ofcom said apologies given by the BBC, the measures it had taken to prevent such an incident and the reassurances it had received from the band beforehand meant the issue had been resolved.
But it said it was "concerned... that the programme's producers were well aware in advance that the original lyrics contained very strong language".
Ofcom said: "In addition, the very nature of the song was about refusing to conform to society's expectations, as suggested through the lyrics 'F*** you, I won't do what you tell me'.
"Yet despite this, the band's singer was able to repeat the lyrics 'F*** you, I won't do what you tell me' four times before the song was faded out by the producer.
"This last point is of particular concern in view of the fact that the producers had full control over the output since it was provided over a live feed from the United States."
Listeners heard presenter Shelagh Fogarty saying "Get rid of it" as the song, first released in 1992, was faded out.
She said afterwards: "Sorry, we needed to get rid of that because that suddenly turned into something we were not, well we were expecting it and asked them not to do it, but they did it anyway, so buy Joe's record."
The BBC accepted the language "was neither appropriate nor justified on a morning programme on Radio 5 Live".
It said Fogarty's apology was repeated by co-presenter Nicky Campbell, while the programme editor issued a public apology on his blog and a full apology was issued to those who complained to the BBC.
Producers, aware of the nature of the song - which did go on to beat McElderry's song to the Christmas number one - had received several assurances from the band members and their representatives that they would change the original lyrics.
In the live interview before the performance, the band gave no indication that they would swear and the first few swear words were changed when they performed live, it said.
The BBC said it accepted there was a degree of risk in asking the band to perform live but had taken reasonable steps to minimise it.
Ofcom concluded: "Given the measures taken by and assurances given to the broadcaster before the broadcast, the conduct of the band during the interview and start of the song performance, and the apologies issued, we consider that on balance, this particular case should be resolved."
It added: "Broadcasters should consider carefully whether it would be appropriate to pre-record material or interviews where there is a material risk of breaching the (broadcasting) code if the output were broadcast live."