Lord Cranborne, who was dramatically sacked by Conservative leader William Hague two weeks ago for agreeing a deal with Mr Blair to keep 91 hereditary peers in a transitional house, writes in a letter to Wednesday's Daily Telegraph newspaper that the proposed royal commission must have "broad terms of reference".

The government is planning to abolish the centuries-old right of hereditary peers to vote and sit in the Lords, without saying who will replace them once they are gone.

Tony Blair "doesn't want an independent commission", says Lord Cranborne

But it has agreed to set up a royal commission on "stage two" reform - what will happen after the hereditaries go.

Lord Cranborne said the commission should have "an eclectic if relatively small membership and should hold the bulk of its hearings in public. Above all it should be chaired by someone whose independence is unquestioned."

"The prime minister fears such a commission. He would like its proceedings to be cursory and its terms of reference narrowly drawn.

"He would like it to recommend an upper house whose membership would be four-fifths appointed.

"He would reject a serving or retired judge as chairman on the grounds that he would be 'too independent'. I hope the public would find such a charade as unacceptable as I do."

Lord Cranborne said the royal commission presents the country with a unique opportunity to examine the purpose and functions of the upper house - and most importantly its relationship with the House of Commons, whose increasing feebleness should be the main concern of all those who believe in parliamentary government.

The blunt message critical of the prime minister is an undoubted boost for Viscount Cranborne's successor, Lord Strathclyde.

Lord Cranborne's sudden sacking sparked four resignations from Tory frontbench peers, including the deputy leader Lord Fraser of Carmyllie.

Two more Tory backbenchers Baroness Strange and Baroness Flather both resigned the whip in protest at the "brutality" of his departure.