- guardian.co.uk, Wednesday 13 January 2010 17.34 GMT
The corporation's editorial complaints unit said coverage of last year's album launch, which included a concert on the roof of Broadcasting House, amounted to "undue prominence for commercial products or organisations" and breached BBC editorial guidelines.
It said the use of the slogan U2=BBC "gave an inappropriate impression of endorsement", and said a reference to the BBC being "part of launching this new album", in an interview between Zane Lowe and U2's Bono on BBC Radio 1, was inappropriate.
Critics complained at the time of the launch, last February, that the BBC had given the band millions of pounds' worth of free publicity across TV, radio and online.
The commercial radio trade body, the RadioCentre, made a formal complaint. Conservative MP Nigel Evans said it was "the sort of publicity money can't buy. Why should licence fee-payers shoulder the cost of U2's publicity?"
But complaints about an edition of Jo Whiley's Radio 1 show, and a BBC News online report of the U2 concert on the roof of Broadcasting House, were not upheld.
The complaints unit said its findings had been discussed at the Radio 1 and sister station 1Xtra editorial meeting.
It added: "In addition, the Radio 1 leadership team have reminded executive producers and presenters about the issues to be considered in relation to judgments about undue prominence, and the distinction between the reporting of new artistic work and commercial promotion.
"The management of BBC marketing, communication and audiences (the division responsible for the U2=BBC graphic) has reminded all staff of the need to consult the editorial policy team in a timely manner for advice when potentially sensitive issues such as commercial interests are involved. A session on working with third parties will be included in marketing, communication and audiences monthly editorial issues training programme."
"We acknowledge the findings and have taken note for the future," a BBC spokesman said.
The unit also upheld a complaint from the RadioCentre about the BBC's coverage of a tour by Coldplay. The "Radio 1 presents Coldplay" website included a link to the websites of ticket agents, which the unit said was "not in keeping with the BBC's guidelines on links to external websites".
The U2 ruling marks the second rebuke for Radio 1 this week, with the editorial complaints unit ruling that a Radio 1 interview with two British National party members was not rigorous enough.
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