U2 released their 12th album last February
The BBC has admitted coverage of the launch of U2 album No Line On The Horizon last February, went too far - giving "undue prominence" to the band.
Critics said the BBC had given U2 "the sort of publicity money can't buy".
The corporation's editorial complaints unit (ECU) acknowledged that radio coverage of the event, including a rooftop concert, breached guidelines.
It added the use of the slogan U2 = BBC "gave an inappropriate impression of endorsement".
RadioCentre, the trade body for commercial radio companies, made a formal complaint over the coverage.
Complaints over the free publicity given to the band on BBC TV, radio and online included those of Conservative MP Nigel Evans, who said it was "the sort of publicity money can't buy".
"Why should licence fee-payers shoulder the cost of U2's publicity?"
The ECU admitted that a reference to the BBC being "part of launching this new album", in an interview between Radio 1 presenter Zane Lowe and U2 singer Bono, was inappropriate.
The body also upheld a complaint that it was inappropriate for the Radio 1 website to contain links to the websites of ticket agents for the band's concerts.
"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," it said, earlier this week.
The surprise concert drew crowds of onlookers in central London
"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."
However, 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.
A crowd of around 5,000 watched the rooftop show, which capped off a day of promotion for the Irish band's 12th studio album, with U2 appearing as special guests on Radio 1.
The band performed four tracks during the 20-minute gig, which was broadcast live on DJ Chris Evans's BBC Radio 2 show.