The Conservatives need to be more critical of the government's Iraq policy, Sir Malcolm Rifkind has said.

In an interview with the Times on Monday, the former foreign secretary warned that the war had seriously damaged Western relations.

"You can only go to war if you believe there is a substantial net benefit to be achieved - that the world will be a better place, a safer place as a result," he said.

"I think one of the great casualties of the Iraq war is one not predicted and that is the huge and ongoing damage to Western unity.

"The deep gulf that has emerged between the United States and most of Europe - that is not only bad in itself but makes the global battle against terrorism that much more difficult."

Candidate

Sir Malcolm, who was recently selected to stand as the Tory candidate in Kensington and Chelsea, insisted that while he did not blame his party for backing military action, it should not stop them criticising the government for its handling of the aftermath.

"Conservatives were in exactly the same position as the public," he said.

"When the government said it had intelligence suggesting Iraq had weapons of mass destruction which could be launched in 45 minutes, which constituted a serious threat to the UK, we were all misled, whether deliberately or unintentionally.

"The party is perfectly entitled, as it is doing, to seek to identify whether there has been incompetence on the part of the government, whether there has been fault or deception and to draw that to the attention of the public."

Conservative government

He declined to be drawn on whether a Conservative government would have gone to war with Iraq.

"The world would have been a slightly different place," he insisted.

"Defence is the handmaiden of foreign policy, and this government has had an incredibly ambitious foreign policy which has far outstripped its capacity or willingness to provide the necessary resources for the armed forces."

Rifkind, who also served as defence secretary in John Major's Cabinet, went on to describe the prime minister's support for President Bush as "too unconditional".

"It is not only the public that is unimpressed by Blair's unconditional support, but ultimately it does damage in Washington as well because unconditionality does not produce respect," he argued.