BAGHDAD (Reuters)

The U.S. military said on Tuesday it had confirmed that the two sons of Saddam Hussein, Qusay and Uday, had been killed in a fierce gun-battle in northern Iraq.

"We're certain that Uday and Qusay were killed," Lieutenant General Ricardo Sanchez told a news conference in Baghdad. "We've used multiple sources to identify the individuals."

Sanchez said the U.S. military had been given a "walk-in" tip that Qusay and Uday were in the villa in Mosul that was raided by U.S. forces earlier Tuesday.

He said it was a six-hour operation that involved various military units including special forces.

"We had a walk-in last night that came in and gave us the information," Sanchez said, adding that they expected to pay the $15 million reward offered for information leading to the death or capture of each of Saddam's sons.

The U.S. military was still working to identify two other bodies recovered from the villa after the battle, he said.

Four coalition soldiers were wounded in the operation and were being treated, he said.