THOUSANDS of BBC staff will stage a nationwide protest today over the "attacks" on the corporation following the Hutton Report.

The action comes after a day of protests over the report into the death of weapons expert Dr David Kelly and the appointment of Lord Butler to chair an inquiry into intelligence gathering.

Demonstrations are due to be held outside BBC offices and studios across the UK in a bid to challenge any attempt to weaken the organisation's independence.

Journalists also want to show their support for Greg Dyke, who resigned as director general last week in the wake of Lord Hutton's findings.

Today's action, which is organised by the National Union of Journalists (NUJ) and the broadcasting union Bectu, follows an impromptu walk-out last week which included workers in Newcastle, York and Middlesbrough.

Yesterday, NUJ general secretary Jeremy Dear said: "The Hutton Report poses a real and grave threat to journalism. It will inevitably mean that journalists face greater pressure to reveal their sources, and it will make sources and whistle-blowers think twice before coming forward."

Meanwhile, Tony Blair came under direct fire yesterday when his opening speech in the Commons debate on the Hutton Report was interrupted by protests from the public gallery.

Several demonstrators were ejected amid shouts of "whitewash" and "no more illegal war" as the Prime Minister attempted to open the six-hour debate.

At one point, the Prime Minister had MPs roaring with laughter when he said: "I somehow feel I am not being entirely persuasive."

As the fourth protestor was bundled to the cells, Speaker Michael Martin took the rare step of halting proceedings - something that has not happened for 17 years.

The public gallery was cleared before the debate continued after a ten-minute delay.

Hours before the debate was disrupted, protestors daubed the gates of Downing Street with whitewash.

Four men and one woman, dressed in wigs and robes, were arrested for alleged criminal damage.

The group - Judges for Justice - said they were demonstrating against the appointment of Lord Butler to chair the review of intelligence on Iraq's weapons of mass destruction.

Labour left-wingers also expressed their objections to Lord Butler's role by tabling a Commons motion against his appointment.

Former defence minister Peter Kilfoyle was among 11 MPs who put their name to the Early Day Motion.

The motion said the former Cabinet Secretary's record during the Scott inquiry into arms to Iraq undermined his credibility as a fair and impartial chairman.

As the Butler Inquiry prepared to get under way, Mr Blair admitted he had been unaware that the controversial "45-minute claim" in the Government's Iraq dossier referred only to battlefield weapons when he asked MPs to vote for war.

Questioned in the Commons, the Prime Minister said he had not known what sort of weapons were being referred to at the time of the vote, on March 18.

Mr Blair's disclosure is likely to raise further questions about the handling of intelligence in the run-up to the invasion of Iraq.

It came as a former intelligence official who gave evidence to the Hutton Inquiry said that crucial material that convinced spy chiefs Iraq was continuing to produce chemical and biological weapons may have been misinterpreted. The dossier, published in 2002, stated that Iraq had chemical and biological weapons capable of being deployed within 45 minutes.

But Joint Intelligence Committee chairman John Scarlett told the Hutton Inquiry it referred only to tactical battlefield weapons and not long-range ballistic missiles, as had been widely assumed in Press reports at the time.

Defence Secretary Geoff Hoon told the inquiry he had known it probably referred to battlefield weapons but had done nothing to correct the media reports.