I went into public life to speak for myself and I will use my own language, my own words

Michael Portillo

It has attracted increasing criticism with some other Tory MPs rejecting it and a former minister calling it "loathsome and offensive".

Conservative Party chairman Michael Ancram insists it was clear from the start party leader William Hague had signed the compact on behalf of the whole party.

Asked about it during a trip to Wales on Friday Mr Portillo said: "No, I haven't signed it because I speak for myself and I have said that I offer equality of esteem to everyone in this country.

"I don't like signing bits of paper and questionnaires thrust in front of me.

"I went into public life to speak for myself and I will use my own language, my own words."

Mr Portillo agreed with the party chairman that Mr Hague had already signed the pledge on behalf of all the party's election candidates.

He added that Mr Ancram would come down "like a ton of bricks" on anyone in the party who used racist or provocative language.

Party vice-chairman Steve Norris has already said Mr Hague expected every Conservative candidate to be signed up to the compact.

The CRE pledge

Labour: 269 of 417 MPs signed Tory: 55 of 160 signed, 4 refused Lib Dem: 45 of 47 signed Others: 9 signed

On Friday, he said candidates who did not want to sign the agreement had an argument but it was not a view he shared.

"I would say there is absolutely nothing in this which isn't in any event perfectly straightforward and which any decent person wouldn't be happy to sign," he told BBC News.

Mr Portillo's comments have dramatically increased the tempo in the debate on racism in politics - and could be seen as an embarrassment to Mr Hague.

The pact commits politicians "not to pitch one group against another for short term political or personal gain".

And it commits the main party leaders - who all signed it - to taking action against any candidates or campaigners who provoke racial prejudice.

On Thursday Mr Portillo pledged "complete loyalty" to Mr Hague following simmering debate about a possible leadership challenge after the election.

But Labour seized on his latest comments, with a spokesman saying he "has demonstrated that the Conservatives under William Hague have no discipline, leadership or unity".

Liberal Democrat leader Charles Kennedy also went on the attack, saying: "If William Hague is going to make the pledge worth more than the paper it's written on, then all candidates must be understood to have signed up to that commitment as well."

Blackmail claim

Earlier Conservative former minister John Gummer accused the CRE of "blackmail" in the way it handled the pledge.

Mr Gummer insisted it was not racist to avoid signing the pledge

Although he did not object to its wording, Mr Gummer labelled it "unconstitutional", declined to say whether he had signed it and defended colleagues who had refused to do so.

Other Tories lining up to voice their opposition to the pledge include former minister Nicholas Soames.

He said: "I think personally it's a loathsome and offensive document and I think it's a corpse of an idea which is trying to drag racism into a general election where no such desire frankly would otherwise exist."

Culture Secretary Chris Smith said Mr Soames' criticism of the compact "beggars belief".

But Dr Raj Chandran, a former member of the CRE and Conservative candidate at the 1997 general election, said the pledge was counter-productive and risked suppressing freedom of speech.

Phil Barnett, director of policy and communications at the CRE, rejected the "blackmail" accusation.

He told BBC News: "It is simply nothing more or less than a brokered agreement between the parties that has attempted to set a standard for the debate about race and race relations in the election."

The row began when Robin Cook attacked recent Tory statements including Mr Hague's warning that Britain could become "a foreign land" under Labour.

The opposition hit back, accusing the foreign secretary of playing the race card himself.