The foreign secretary is nothing more than "Blair's errand boy", Michael Ancram has said.

"The day was when a foreign secretary stood tall in any cabinet - but not Jack Straw," he told delegates in Blackpool.

"He is now nothing more than Blair's errand boy."

Branding Tony Blair the "high priest of spin", the shadow foreign secretary repeated calls for an independent judicial inquiry into the events leading up to the war.

"What was wrong was the way this prime minister approached the war," he said.

"We pressed him to make a case that the British people could trust. He failed to do so. Instead he bent and twisted the truth for his own ends.

"Mr Blair. The case was sound. There was no need to lie. You didn't need to stretch the truth. You didn't need to manipulate the intelligence material.

"You didn't need to claim that your dodgy dossier was intelligence-based when it was not. You did not need to claim personal knowledge of WMD that evidently you did not have.

"This prime minister should have trusted the British people. But the culture of spin in Downing Street was just too strong.

"The government should now end the confidence sapping drip-drip of accusation and counter-accusation.

"They should - as we have long asked - set up a comprehensive independent judicial inquiry into the events leading up to the war and its aftermath."

Tony Blair has lost the public's trust for good, insisted the Tory deputy leader, said Ancram.

"Prime minister. The British people don't like you anymore, the British people don't trust you anymore, they don't believe you anymore, you have let them down, and for that they will not forgive you," he said.

Ancram followed fellow shadow cabinet colleagues in criticising the Liberal Democrats for their policies.

"We need a foreign policy that people can trust. You certainly won't get that from the Liberal Democrats," he said.

"Still the dirtiest fighters in British politics. No principles, no ethics and no beliefs. All things to all men."

The shadow foreign secretary also turned his attention to the proposed European Union constitution, which was debated in Rome over the weekend.

Conservatives would oppose the document "with everything we've got", he insisted.

"Tony Blair has already thrown in the towel. And now we hear he is selling-out our rebate," he said.

"We will fight this damaging constitution with everything we've got.

"For a start, the British people have the right to say yes or no in a referendum. Other EU countries are having referendums to decide.

"Mr Blair what is wrong with the British people that we cannot be trusted to decide?

"We will promote a petition to parliament requiring a referendum, because even this prime minister cannot ignore forever the collective voice of the British people."

His comments drew a withering response from the foreign secretary.

"Mr Ancram's speech says everything about the Conservative Party's visceral opposition to the European Union and Britain's place in it, under the leadership of Iain Duncan Smith," said Straw.

"The Tories would lead Britain to the exit door of Europe, putting at risk British jobs, British trade and British national interests."

He also challenged Ancram's stance on Iraq - accusing him of changing sides.

"On Iraq, Mr Ancram is in danger of falling prey to the very attack of opportunism that he makes against the Liberal Democrats, and I regret that the shadow foreign secretary now appears, to paraphrase his speech, to be 'blowing in the wind' on this issue."