Radio 2 was once the comfy home of Jimmy Young and Wurlitzer melodies, but now broadcasting watchdogs have told the station to cut out foul language.

Ofcom has found Britain’s most popular radio station in breach of broadcasting rules after a lunchtime f-word outburst from Jack Dee during a comedy programme. In an echo of last week’s row over the BBC One documentary on the Queen, the BBC admitted that it had not checked for offensive material before the broadcast.

The regulator said it was not the first time that Radio 2, whose star presenters now include the controversial comic Russell Brand, had been censured for inappropriate language.

Listeners complained about the programme, The Green Guide to Life, a sketch show about the “complications and confusion of modern-day living”, broadcast at 1pm in April. Dee was heard to say, “What do you mean, f*** off”, during the Saturday show. The BBC said that the language was “completely inappropriate for broadcast” and apologised.

As with the Royal Family documentary, the prerecorded programme was made for the BBC by an independent production company. It had been intended for a late-evening broadcast but the producers did not indicate that it contained strong language.

Ofcom said: “This error exposed a weakness in the broadcaster’s compliance procedures. Further, this is not the first occasion on which inappropriate language has been transmitted on Radio 2.”

Last year, during a live interview on Jonathan Ross’s Saturday morning show, Rupert Everett used the f-word twice in quick succession, as well as a slang word to refer to female genitalia.

Ofcom added: “It is the clear responsibility of the broadcaster to ensure that all material, irrespective of who originally produced it, is suitable for broadcast and appropriately scheduled.”

The watchdog warned all broadcasters over a rise in cases of programmes originally produced for a postwatershed time slot being repeated unedited before 9pm. ITV and Five have admitted that human error had led to the early scheduling of programmes containing foul language.

Ofcom said that failure to have suitable compliance procedures in place could lead to “regulatory action” and a fine of up to £250,000.

Radio 2’s audience has soared to 13 million with star signings such as Brand and Chris Evans bringing new, younger listeners to the station. Old favourites such as Your Hundred Best Tunes have given way to TV-friendly DJs such as Alan Titchmarsh and documentaries about punk rock.

However, commercial stations have complained that Lesley Douglas. the Radio 2 Controller, has used the power of the BBC chequebook to snap up big names. The BBC Trust said that talent costs had become an issue of concern and asked Radio 2 to clarify its “distinctiveness and contribution to the BBC’s public purposes”.

After criticism of inappropriate language used by Chris Moyles at the sister station Radio 1, executives vowed to fine DJs for repeat offences.

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