The BBC breached its own guidelines in promoting U2's last album and a Coldplay tour, its editorial complaints unit has ruled.
The body, which examines whether the BBC has broken its broadcasting rules, said a stunt to mark the launch of U2's No Line On The Horizon, in which an on-screen graphic was displayed with the slogan "U2=BBC", was "inappropriate".
Another complaint about a "Radio 1 presents Coldplay" website, which included a link to ticket agents for the band's tour, was ruled to have broken guidelines about links to external sites.
The volume of coverage given to the U2 launch last February - including a rooftop performance on Broadcasting House - drew criticism at the time.
Some said it was unfair for the band to be given millions of pounds of publicity and Conservative MP Nigel Evans asked: "Why should licence fee-payers shoulder the cost of U2's publicity?"
Commercial radio body The RadioCentre then made an official complaint.
The BBC's complaints unit said the logo gave an "inappropriate impression of endorsement".
And a reference to the corporation being "part of launching this new album" in an interview that U2 frontman Bono gave to Radio 1's Zane Lowe was ruled not to be appropriate.
Further complaints about an edition of Jo Whiley's Radio 1 show and an online report of the rooftop gig were not upheld.
The station's executive producers and presenters have been reminded about the distinction between reporting new artistic work and commercial promotion.