Chilcot inquiry points out that Tony Blair, Jack Straw and Gordon Brown have given 'three rather different explanations', and asks foreign secretary to explain why he voted for war

Ministers have given the Iraq inquiry different reasons for the decision to go war, David Miliband was told today.

At the start of the foreign secretary's evidence to the Chilcot panel, Sir Roderic Lyne, a member of the inquiry panel, said it had heard "three rather different explanations as to why we took military action against Iraq in 2003".

Tony Blair emphasised the need to impose regime change on Iraq, Lyne said. But Jack Straw, the foreign secretary at the time of the war, stressed the importance of dealing with Iraq's presumed weapons of mass destruction, Lyne said.

And Gordon Brown, when he gave evidence on Friday last week, said he supported the war because he thought the will of the international community had to be enforced.

Given the three views expressed by Blair, Straw and Brown, Lyne asked Miliband to explain why he voted for the war in March 2003, when Miliband was a junior education minister.

Miliband replied: "I do not see the inconsistencies in the three sets of evidence that you describe."

He said that, before he voted for war, he read one of the reports from Hans Blix, the UN weapons inspector, and he believed that established a "prima facie" case for Iraq having WMD.

In his evidence Blair said the inquiry should consider what would have happened if the Iraq war had not taken place. He said that an Iraq still led by Saddam Hussein, competing with Iran to acquire WMD and support terrorism, could be an even greater threat today than Iraq was in 2003.

Lyne asked Miliband if Blair's analysis was correct. Miliband said that this was a very important question but that it was "unanswerable".

Miliband went on: "The authority of the UN would have been severely dented. If, in the hypothetical case you are putting, we had marched to the top of the hill of pressure and marched down again without disarming Saddam Hussein, that would really have been quite damaging [to the ability of the UN to work together]."

Miliband also insisted that the opposition to the Iraq war among the international community was not damaging British diplomacy today.

"I do not feel today, in the work I'm doing at the Foreign Office and doing at the UN, that Iraq is thrown at us ... It's quite striking the extent to which the waters at New York [where the UN is based] close over and work carries on."

Some countries respected Britain because of what happened in Iraq, he said.

"People in the region will respect those who will see through what they say they favour, even though they disagree with it, and would say to me: 'You have sent a message that when you say something, you actually mean it,'" Miliband said.

The foreign secretary also told the inquiry panel that they should not learn the "wrong lesson" from the war.

"The wrong lesson would be that Britain should leave international engagement to others," he said.

"We must not be a country that turns our back on the world. Because if we do we will be much poorer as a result, in all senses of the world."

Miliband, the foreign secretary since 2007, will be the last minister to give evidence to the inquiry before the election. In an interview published ahead of his appearance at the inquiry, Miliband said it would be "stupid" to pretend that the Iraq war had been a total success.

The foreign secretary said that history's verdict on the war would be "balanced", and said that it could take another six or seven years before the situation in Iraq stabilised.

Asked if he agreed with the proposition that the war was justified, Miliband told the Daily Telegraph: "That falls on two counts. One, it is too glib about the loss of life and the reverses. And it's too black and white. There's a ledger, and it's still being added to. There is a positive and a negative. It's a balance, and history's version will be a balanced judgment."

Miliband said that he did not have "sleepless nights" about the war. But that did not mean that he did not acknowledge the problems associated with it.

"There are hard questions to be asked of anyone who supported the war," Miliband said.

"It would be stupid to pretend the balance is all on one side of the ledger. We haven't lost the peace, but a lot of people have lost their lives … It was much easier to win the war than the peace."

Miliband described Iraq as a "post-conflict situation with quite a lot of conflict still going on". He said that the next six or seven years would be "absolutely critical" in deciding how Iraq developed.

He also insisted that Britain would not have gone to war if it had been known that Iraq did not have weapons of mass destruction.

"If there was convincing evidence there were no WMD, there would have been no UN resolution and ... no [parliamentary] vote."