HOLYROOD'S vital committee system is no longer fit for purpose, a group of the parliament's most senior MSPs have warned.

In an outspoken attack, elder statesmen Hugh Henry, Duncan McNeil and Michael McMahon accused SNP chiefs of using their in-built majorities on cross-party committees to close down scrutiny of the Government.

They spoke out after The Herald learned that demands for a detailed investigation into SNP benefits plans were this week secretly voted down by Nationalist MSPs on the welfare reform committee.

The snub follows a bitter row over the European committee's decision to block an inquiry into an independent Scotland's membership of the EU, and clashes within the health committee that saw SNP members accused of resisting demands for care watchdogs to give evidence in case it could embarrass ministers.

Labour veteran Mr Henry, who has served on a string of committees, said SNP MSPs were routinely receiving lines of questioning for ministers and other witnesses from party whips.

He also condemned the increasing use of private sessions – demanded by Nationalist MSPs – to control the work of the committees away from the eyes of the press and public.

He said: "The committees were held up to be cutting edge of the Scottish Parliament. What we are now seeing is a deliberate attempt to dumb down the committees, to neuter them and avoid any critical comment about the Government.

"We are heading in a very dangerous direction for Scottish democracy, where criticism and dissent are being eliminated."

Mr Henry added: "If you think back to the early days of the Parliament, the whips had very little influence on the committees. Now committee members are routinely taking their line of questioning from the whips."

The latest row came over a bid by opposition MSPs on the welfare reform committee to demand greater financial scrutiny of Government plans for benefits due to come under Holyrood control next year.

Last week the committee staged a high-profile hearing in which one campaigner, Henry Sherlock, 50, launched a fierce attack on UK Government reforms, telling MSP he had been reduced to a "blind beggar".

However, in private SNP MSPs blocked calls for more detailed information on Scottish Government plans.

Labour's Michael McMahon, the committee convener, said: "Labour members on the committee were concerned at the extent to which SNP MSPs were prepared to block a more open process for the scrutiny of the Government's Welfare Bill despite demands for it from stakeholder groups. I have never known such a blatant manipulation of evidence in my 13 years in the Parliament."

Duncan McNeil, convener of Holyrood's health committee, claimed the SNP was preventing its MSPs from fulfilling their wider role as parliamentarians.

He said: "The committees are not fulfilling their role. They are no longer fit for purpose. It's a fundamental issue if the committees cannot hold the Government to account."

But the MSPs' complaints were dismissed by Christine Grahame, the SNP convener of the justice committee.

She said: "There are some good conveners and some not so good and it's nothing to do with their politics. It is all about who is sitting in the chair.

"My committee has given the cabinet secretary quite a rough time about plans to end the need for corroboration in criminal cases and about cuts to legal aid. I would never suppress a question from any committee member."