Tony Blair has warned that the allegations of violence against Iraqi prisoners are "extremely serious".

Quizzed in the Commons by Michael Howard, the prime minister said that MPs should wait until the investigation into the Daily Mirror photographs is complete before making any judgement.

"If they are true that is completely unacceptable," said Blair. "On the other hand if they are not true that is extremely serious."

Meanwhile, the Commons defence select committee has demanded that Mirror editor Piers Morgan gives evidence on how his newspaper acquired the controversial photographs.

"We support entirely the determination of ministers and army chiefs that these matters should be thoroughly investigated by the special investigation branch of the Royal Military Police," said the committee.

"It is incumbent on the Daily Mirror to cooperate fully with these investigations.

"We have decided that we will take an early opportunity to call the editor of the Daily Mirror to appear before us.

"This will give him a chance to substantiate his newspaper's allegations. It will enable us to satisfy ourselves whether he and his staff have acted responsibly in how they have handled this matter.

"We will hold this session in the context of our already announced inquiry into the continuing operations in Iraq."

Sovereignty

Speaking in the Commons the prime minister went on to commit the UK to giving "complete and full sovereignty" to the people of Iraq.

But he added that the Iraqi people had to recognise that British troops will remain in the country in order to "provide the security necessary for democracy to work".

For the Conservatives, Michael Howard said British servicemen and women were "making enormous sacrifices in Iraq".

And he warned that the current media reports of violence against prisoners was doing "enormous damage".

If the investigation proved that the allegations were true, Howard said the "severest action should be taken".

But also warned that Mirror executives would have to face the music if the photographs proved to be false.

"This is a matter of the utmost seriousness for which the editor of the Daily Mirror will have to take full responsibility," said Howard.