Outgoing US Defense Secretary Donald Rumsfeld is making a surprise visit to Iraq to say farewell to US troops, days before he is due to leave office.

"The secretary is in Iraq to express appreciation to the troops," said a Pentagon spokesman, giving no further details of his itinerary.

Mr Rumsfeld announced his resignation in November, after the Republicans lost heavily in mid-term elections.

His successor, former CIA chief Robert Gates, takes over on 18 December.

Mr Rumsfeld will "thank both the troops and their families for the sacrifices they are making," said Air Force Lt Col Todd Vician, a Defense Department spokesman.

Mr Rumsfeld left for Iraq on Friday, the spokesman said, after he had given an emotional farewell speech to Pentagon staff.

'Challenging period'

Addressing an audience of troops and Pentagon staffers, Mr Rumsfeld praised them for their dedication.

"I can't think of a more challenging period... in the 59-year history of this department than these past years," he said.

He praised the work of the military in Iraq and Afghanistan.

"Each of you and future generations of Americans, as well as future generations of Iraqis and Afghans, will be able to look on these past years as a time of enormous challenge and historic consequence," he said.

But he said patience and staying power were needed to succeed.

"To pull out precipitously (from Iraq) and inject that instability into the situation there in that country, and in that region, I think would be a terrible mistake."

He said he was "stunned" by the news of prisoner abuse at Abu Ghraib.

"Clearly, the worst day was Abu Ghraib, seeing what went on there and feeling so deeply sorry that that happened," he said in a question-and-answer session.

But he hit out at "grossly uninformed" charges in the media over the Guantanamo Bay detention camp.

When asked how he would like to be remembered, he quipped: "Better than the local press."

Photo caption

Outgoing US Defense Secretary Donald Rumsfeld