The BBC is facing legal action over its coverage of the Queen's diamond jubilee, after the anti-monarchy campaign group Republic served a "letter of claim" threatening to take the corporation to judicial review.

Republic - represented by Sarah McSherry, partner at Christian Khan Solicitors - claims that the BBC has breached its legal duty of impartiality by promoting and celebrating the jubilee, rather than reporting the facts.

The letter describes the BBC's coverage as "a vital campaigning tool for the monarchy in promoting its cause" and accuses the corporation of attempting to "influence members of the public to support the institution of monarchy".

It singles out the BBC's decision to co-organise a celebratory jubilee concert as representing "an outrageously blatant and complete disregard" for its obligations.

The letter seeks a public admission from BBC executives that its jubilee coverage is in breach of its charter and calls on the corporation to reform its future coverage of the monarchy and royal family.

The BBC's litigation department has responded to the letter, saying that the claim will be "vigorously opposed".

The legal action is the latest twist in the ongoing battle between Republic, which is holding a major anti-monarchy protest at the Thames diamond jubilee pageant on June 3, and BBC executives.

In February, emails leaked to the pressure group revealed that the BBC refused to interview anyone with a "bad word against the Queen" for its forthcoming jubilee documentary.

The leak came just days after Republic wrote to Chris Patten, the chair of the BBC Trust, to demand an investigation into "distortions, half-truths and fabrications" contained in the Diamond Queen series, presented by Andrew Marr.

Republic's chief executive Graham Smith said:

"The BBC has a legal duty of impartiality when it comes to controversial subjects like the monarchy. Reporters are required by law to ensure that a full range a views and perspectives are heard. We hope this action will focus attention on the BBC's obligations and lead to fundamental reform of its relationship with the Palace."

"We're not asking the BBC to ignore the jubilee, but simply to report it as a political event about which there are a wide range of views. All too often, the BBC comes across as part of the royal PR machine - ignoring or dismissing the quarter of the population that wants to see the monarchy abolished and many more who wish to see it changed or challenged."

"Polls show that support for the monarchy has actually weakened in the past year, while our campaign has continued to grow - yet the BBC acts as if the royal family is universally adored."

"The BBC must learn that it is there to report on the monarchy, not to celebrate and promote it. The same level of journalistic scrutiny must be applied to the palace, the royal family and all their PR events that is applied to politicians and other public servants."

NOTES

The letter of claim can be viewed online at http://www.republic.org.uk/bbclegalletter.pdf Republic's letter to Chris Patten can be viewed online at http://www.republic.org.uk/pattenletter.pdf

Full details of Republic's June 3 protest at the Thames diamond jubilee pageant are available at www.republic.org.uk