If she thinks there is a conspiracy against her, she must be off her head

Commons commission source

In an interview with BBC Radio 4's Today programme, Ms Filkin suggested "powerful individuals" within Parliament tried to frustrate her by encouraging a "whispering campaign" against her.

Sources have told her that senior civil servants - and even ministers - had put pressure on witnesses and attempted to discredit her inquiries.

Now it has emerged that Nigel Wicks, chairman of the independent committee on standards in public life, wrote to Commons speaker Michael Martin a week ago expressing concerns about the shortening of the commissioner's working week.

'Job devalued'

His letter would appear to support Ms Filkin's central allegation - that the role of the standards watchdog was being reduced in importance.

Former MP Martin Bell says he was head-hunted for the post but refused.

"I don't see who is going to take this job," he said.

Bell says he was head-hunted

But it is understood about 40 applications have been received, including one from former Guardian editor Peter Preston.

Mr Preston said he actually wanted Ms Filkin to continue and he called for a completely new way of choosing the commissioner.

Mr Martin, who chairs the House of Commons Commission - in charge of appointing Ms Filkin's successor - is making a statement later on Wednesday expected to address the controversy.

The row has prompted the commission to hold an emergency meeting and while there has been no public comment, its members are angry.

One commission source told BBC Radio 4's World At One programme: "If she thinks there is a conspiracy against her, she must be off her head."

There was stinging criticism too of Ms Filkin for being politically naive and for having an inflated view of her own importance.

Downing Street's distance

Prime Minister Tony Blair's spokesman said the affair was a matter for Parliament and said "if" Ms Filkin had any evidence of ministers or civil servants pressurising her she should present it to parliament.

The role of standards commissioner was created in the aftermath of the 'sleaze' scandals of the early 1990s.

If the House is truly serious about having the scrutiny done by an independent office, which is what I believed it to be, then the House does need to protect that

Elizabeth Filkin

It involves checking complaints about the financial declarations and interests of MPs.

Peter Mandelson, Keith Vaz, Geoffrey Robinson, John Major and William Hague were among the high-profile figures to be investigated by Ms Filkin.

Announcing her decision to quit, Ms Filkin said Speaker Michael Martin had undermined her role and that some MPs applied "quite remarkable" pressure against her.

She told Today the whole future of Parliamentary scrutiny was now at risk.

Early warnings

Ms Filkin claims the campaign against her had begun within weeks of her taking up the post.

"Very early on in the post...some people were talking to the press and saying I wasn't a suitable person to be doing the job even before I had published my first report (into Peter Mandelson)."

She refused to name the people behind this alleged campaign but stressed opposition to her investigations was not just restricted to the Labour Party.

'Over-zealous'

Ms Filkin denied accusations that she had been "over-zealous" and strongly defended the way in which she had conducted her inquiries.

Mr Wicks' letter to the speaker, who chairs the House of Commons Commission, the body responsible for selecting a successor to Miss Filkin, criticised the decision to reduce the hours for the job to three days a week from four.

"We are not aware of any evidence that suggests that the commissioner's workload is likely to fall, nor that the commissioner's office has received recently significant additional resources."

The Conservatives are calling for an independent investigation into Ms Filkin's allegations.

Sources at the committee on Standards in Public Life say they will not begin their inquiry into the procedure surrounding the non appointment of Ms Filkin until "well into the New Year".