President George Bush last night finally apologised for the abuse and humiliation of Iraqi prisoners by US soldiers - as more shocking pictures were published.

He said the scenes of mistreatment had made Americans "sick to our stomachs".

Mr Bush told Jordan's King Abdullah II: "I was sorry for the humiliation suffered by the Iraqi prisoners and the humiliation suffered by their families.

"I told him I was as equally sorry that people seeing those pictures didn't understand the true nature and heart of America," Mr Bush said, standing outside the White House alongside King Abdullah.

With Mr Bush were Secretary of State Colin Powell, Vice-President Dick Cheney and national security advisor Condoleezza Rice.

Vowing that guilty parties would be brought to justice, Mr Bush said he wanted to ensure that there was not a wider problem in US-run military prisons that required attention.

"It's a stain on our country's honour and our country's reputation," said the President.

"I am sickened by what I saw and sickened that people got the wrong impression."

Mr Bush's statement went beyond his comment on Wednesday that the abuse of prisoners was "abhorrent" and "does not represent the America that I know". His lack of an apology then was striking.

Scenes of mistreatment have been broadcast around the world, drawing international condemnation and prompting outrage in the Middle East.

The President said he told the king: "Americans like me didn't appreciate what we saw, and it makes us sick to our stomachs.

"I also made it clear to His Majesty that the troops we have in Iraq who were there for security and peace and freedom are the finest of the fine."

For his part, the king said, "We're all horrified by the images" of torture and abuse.

He said he was confident that US investigations would find the guilty parties.

The President said he had assured the king that "people will be brought to justice in a way commensurate to how our system works".

Mr Bush also rejected calls for the resignation of Defence Secretary Donald Rumsfeld.

"He's an important part of my Cabinet and he'll stay in my Cabinet," he said.

The President stood by Mr Rumsfeld, despite the publication yesterday of more photographs showing US soldiers abusing Iraqi prisoners.

The new pictures - taken last year and including one of a naked Iraqi held on a dog lead - piled further pressure on the Bush administration, which has been seriously damaged by the affair.

Calls for Mr Rumsfeld's resignation are growing on Capitol Hill, where there is anger that Congressmen and women had not been told about an earlier military report which exposed the abuse.

Mr Rumsfeld has been called to appear before the Senate Armed Services Committee today to explain why Congress was not properly informed of the affair.