Some witnesses were left very frightened by "bullying tactics" adopted by some MPs involved in sleaze investigations, according to Parliament's former watchdog.

Elizabeth Filkin said the vast majority of MPs cooperated in full with her inquiries into complaints against them but in "occasional" cases there was "backstabbing" and pressure on witnesses.

Filkin's high profile inquiries

Keith Vaz John Reid Peter Mandelson Geoffrey Robinson John Major

Appearing before the Committee for Standards in Public Life on Monday, she also accused Commons Speaker Michael Martin of attacking the independence of her post late last year.

The former watchdog also called for MPs' expenses claims to face tough new checks.

New scrutiny has been introduced on the costs of MPs' staff but Ms Filkin says how they spend taxpayers' money on housing and transport must also come under more rigorous inspection.

'Mayhem'

The former watchdog quit her job in February complaining she was the victim of a whispering campaign.

In a statement to the committee, she said: "A few members seemed willing to adopt the tactics of bullying and backstabbing during investigations of complaints.

"Sometimes these silenced a witness, frightened newspaper editors, put pressure on committee members and caused mayhem and additional work."

Boothroyd made a veiled attack on Filkin

Ms Filkin suggested Mr Martin undermined her independence by instructing her near the end of her time in the post not to talk to the media.

"I don't think that being instructed was compatible with independence and I was very surprised."

Mr Martin has already rejected claims that he undermined Ms Filkin.

'Whispering campaign'

The former watchdog said self-regulation was the best way of ensuring high standards from MPs.

But she added: "The problem that I see is that occasionally the political pressures are intense on the members of the standards and privileges committee.

"Because that is the case and it's a fact of political life the self-regulatory arrangements need buttressing."

Peter Bottomley was one of Filkin's chief supporters

If evidence was given on oath it would help those witnesses who were frightened about what would happen if they told the truth, suggested Ms Filkin.

The parliamentary commissioner, now Philip Mawer, should have more powers to be able to call for papers and witnesses, Ms Filkin suggested.

Under the existing rules, the commissioner has to ask the Commons Standards and Privileges Select Committee to do that but Ms Filkin said that did not always happen.

Media links

Ms Filkin's resignation in February partly prompted the Committee on Standards in Public Life's inquiry into whether there were tough enough regulations governing MPs.

Earlier, Ms Filkin came in for thinly veiled criticism for failing to keep complaints about MPs out of the press when she was parliamentary sleaze watchdog.

Former Commons Speaker Betty Boothroyd said that it was wiser for the parliamentary standards commissioner not to talk to the media or give lectures on their role.

Friend and watchdog

Lady Boothroyd told the committee that self-regulation was the best method for a sovereign parliament.

The commissioner should be a servant of the house, with a responsibility for being a friend and confidant of MPs while vigorously implementing the rules, argued Lady Boothroyd.

Arrangements for independent scrutiny and monitoring and the role of MPs as holders of public office are also part of its inquiry.

Ms Filkin decided not to re-apply for the job she held from 1999 amid allegations that her investigations had been undermined by senior figures in Parliament.

Her departure prompted Tory MP Peter Bottomley to resign from the Commons standards and privileges committee in protest.