The BBC must make its coverage of Europe "more demonstrably impartial", an independent inquiry has said.
The BBC's coverage is under scrutiny
The report, commissioned by the BBC governors, found no evidence of deliberate bias in BBC reporting.
But it said there was a "widespread perception" of "certain forms of cultural and unintentional bias" which had to be corrected.
BBC News has set up a working group to examine the report in detail and to draw up its response to the findings.
The governors said in a statement: "We are pleased that the panel found no evidence of deliberate bias in the BBC's coverage of EU matters.
"That said, we note the panel's conclusion that 'there is a widespread perception that the BBC suffers from certain forms of cultural and unintentional bias' and that 'the BBC's coverage of EU news needs to be improved and to be made more demonstrably impartial'.
"On the evidence of the MORI research that informed the Panel's report, the BBC is not succeeding in providing basic accessible information on the topic of Europe and urgent action is needed."
In its response to the report, the BBC said: "We agree that the subject of Europe is extremely complex and challenging and one where we need to review any weaknesses and develop a stronger creative response.
"The BBC has an important responsibility to provide accessible, accurate and fair information and analysis on this subject to all our audiences.
"Helen Boaden, the new director of BBC news, will be chairing a group that will examine the report's findings in detail and will formulate a response to be presented to the BBC's Journalism Board and Governors at the end of next month."
The report was commissioned by the BBC governors as part of a series of impartiality reviews of subjects where the BBC's performance is often questioned, such as rural affairs and religion.
But - in line with new governance arrangements - it was the first review to be conducted outside the BBC management chain and the first to be published in full.
The inquiry said it had found an "institutional mindset" at the BBC when it came to the EU and a tendency to "polarise and over-simplify issues".
It also claimed there was a "measure of ignorance of the EU on the part of some journalists" and "a failure to report issues which ought to be reported, perhaps out of a belief that they are not sufficiently entertaining".
"Whatever the cause in particular cases, the effect is the same for the outside world, and feels like bias," the report concludes.
Among its 10 recommendations, the report says there "needs to be a better and more impartial coverage of the EU to explain major issues to a wider audience".
It adds: "The problem of ignorance among BBC journalists on the EU issue must be addressed as a matter of urgency.
"The BBC should devote more resources to training programme makers and researchers so that they better understand the EU."
The inquiry team included Lucy Armstrong, a business consultant, and Sir Stephen Wall, an adviser to Cardinal Cormac Murphy-O'Connor - both considered euro-enthusiasts.
The eurosceptic viewpoint was represented by Rodney Leach, who chairs Business for Sterling and Nigel Smith, head of the No-euro campaign.