Mark Radcliffe (left) let slip a swear word to co-host Riley

Ofcom censured an edition of the Mark Radcliffe show last October when the presenter let slip a profanity while in conversation with co-host Marc Riley.

The use of bad language during an early afternoon was said to be "ill-judged" by Ofcom, despite being accidental.

Ofcom also upheld a complaint about an offensive song lyric played during the Zane Lowe show, also in October 2003.

The BBC responded to the complaint by saying the offensive word had been heavily disguised using editing.

'Most offensive'

But Ofcom concluded that the word remained "clearly audible" and was a term fitting the "most offensive" category.

They added that more stringent guidelines for vetting tracks had been introduced since the programme was transmitted.

Specialist music shows such as Zane Lowe's evening slot are permitted to play full versions of records if they "pass quality tests and are a genuine expression of popular culture", according to BBC producer guidelines.

But they add that very offensive language would still normally not be acceptable.

Not suitable

Mark Radcliffe and Marc Riley's long-running double act on Radio 1 came to an end earlier this year.

The pair have gone on to present separate programmes on other BBC networks, with Radcliffe lined up for Radio 2 and Riley gaining a slot on digital station 6 Music.