The BBC is today braced for some of the strongest criticism likely to emerge from Lord Hutton's report.

Both the corporation's standards of accuracy and its initial failure to accept mistakes in the way it handled its row with the government are set to be highlighted in the law lord's report.

The BBC has now admitted that errors were made and recently launched a pre-emptive overhaul of its mechanisms for dealing with complaints.

The entire row has been based on a report for the Today programme by journalist Andrew Gilligan. Broadcasting at 6.07am on May 29 last year, Gilligan said the government had knowingly made a false claim in its intelligence dossier that Iraq could launch weapons of mass destruction within 45 minutes.

The reporter said he had been told by "one of the senior officials in charge of drawing up that dossier...[that] the government probably knew that that 45 minute figure was wrong, even before it decided to put it in".

Many independent observers have since agreed that evidence heard during the inquiry shows that Number 10 chief of staff Jonathan Powell and former communications director Alastair Campbell did indeed make contributions that had the effect of strengthening the dossier.

But the BBC has now accepted as unfounded the claim that ministers used the 45 minute figure knowing it was wrong.

After broadcasting the controversial report, the BBC and Number 10 engaged in an increasingly embittered war of words over whether it was right for the report to have been aired.

With ministers keen to discredit the BBC's report, head of news Richard Sambrook, director general Greg Dyke and chairman of the board of governors Gavyn Davies all weighed in to stress the independence of the corporation.

But at the same time, Today editor Kevin Marsh was warning in internal emails that the story was "a good piece of investigative journalism marred by poor reporting".

It also emerged that the governors and other senior managers failed to fully investigate the accuracy of the report before leaping to its defence.

The BBC has since overhauled its complaints system with the appointment of a new deputy director general and has also banned journalists from most freelance writing.

The corporation has also accepted that Downing Street should have been notified before the controversial report was aired.

Journalist Andrew Gilligan is also awaiting Lord Hutton's judgement.

Having retained his own counsel during the inquiry, the reporter will be keen to see if the law lord upholds his version of events.

His claims that Dr Kelly suggested that Alastair Campbell was responsible for "sexing up" the intelligence dossier have come under intense scrutiny.

The Kelly family has branded Gilligan's account unreliable as it seeks to prove that the scientist did not make any unauthorised comments to the journalist.

But his descriptions of Kelly as "one of the senior officials in charge of drawing up that dossier" have also been questioned for their accuracy.

Gilligan's conduct also raised eyebrows when it emerged that he had emailed a member of the Commons foreign affairs committee disclosing details of a conversation that a fellow BBC reporter had with Dr Kelly.

This move was described as unacceptable by Dyke when he gave evidence to the inquiry.