The prime minister has taken part in a private audience with the Pope at the Vatican in Rome.

Ahead of the meeting, Tony Blair called for the world to "speak with a single voice" in order to exert maximum pressure on Iraq.

During his visit to the Vatican, the prime minister heard pleas for strenuous efforts to avoid war.

But amid claims that he was set clash with the Pope, Blair defended his hardline stance on Iraq.

He said that it was clear that "without the possibility of force being used the UN inspectors would never have gone back into Iraq at all".

Blair said that a "clear united message on behalf of the world community" was needed to put pressure on Saddam to cooperate fully with the UN inspectors.

"I very much hope that we will speak with a single voice," Blair added.

He said that UN resolution 1441 demanded full Iraqi cooperation.

"If there is not such cooperation then resolution 1441 makes it clear that Saddam is in breach of the UN will."

"If we cannot disarm him peacefully...are we just going to ignore the issue and hope it will go away?" asked Blair.

"Even now we can avoid conflict, but we cannot avoid it by weakness."

Following criticism from senior churchmen, Blair defended the morality of any war.

He told journalists that Saddam would be responsible for a conflict.

"Does anyone believe he is really cooperating now?" he asked during a news conference in Rome.

"Who is it, therefore, that is responsible for conflict if it comes?

"Us, who have done every single thing we can to solve this peacefully, or him who refuses to abide by the clearly expressed view of the whole of the international conflict?"

The US maintained, however, that there is no division between the pontiff and those calling for military action unless Saddam disarms.

Jim Nicholson, American ambassador to the Holy See, said the Pope had "exactly the position of president Bush" on war in Iraq.

"The most important thing on the line is the security of innocent people throughout the world," said Nicholson.

"And the president has the responsibility under the catechism of the Catholic Church, not just the right as a duly elected public authority, but the obligation at certain times and in certain conditions to take action to protect innocents."