A US-led occupation official is to hold a press conference in Baghdad on Wednesday afternoon where the details of the battle are expected to be revealed.
Uday and Qusay were killed during an US raid in the Iraqi town of Mosul on Tuesday.
The two are thought to have died in a fierce, six-hour gun battle after occupation forces received a tip off that both Uday and Qusay were in the villa.
US spokesman General Ricardo Sanchez confirmed that the information had come from "multiple sources" and DNA testing would officially identify the two bodies.
It now appears two of Iraq's most wanted men were located and killed after they were spotted by a Mosul resident who reported his sightings to the US.
The resident could get as much as $15 million in reward from the American occupiers.
There were reports of celebratory gunfire in Baghdad during Tuesday night, as news of the deaths filtered out. More sceptical Iraqis were asking to see photographic evidence of the corpses.
US Forces have told journalists that although the bodies were "badly damaged" they were confident Qusay and Uday were among the dead.
Another corpse, that of a 14-year-old boy, is thought to be Qusay's son.
The world's media went into overdrive trying to get confirmation, but mixed messages from the Pentagon over the identity of the dead bodies, found in the villa in Mosul, added to wild speculation and confusion during Tuesday evening.
CNN television quoted an unnamed US official as saying the government was reasonably certain that Uday and Qusay Hussein had "met their Maker."
The official said four Iraqis were killed after 200 US troops surrounded and destroyed a house in Mosul in pursuit of key allies of the ousted Iraqi leader.
The US military has confirmed it killed four “high level” Iraqis and is currently trying to identify their bodies through DNA testing.
Al Jazeera’s correspondent in Iraq, Yasser Abu Hilala, said residents of the Al-Falah area said they had seen Qusay and Uday earlier in the day.
But another US official told AFP that it was "too early to speculate" about the identities of the men.
He cautioned: “We’ve been down this road before.”
And Dr Martin Navias, of the UK's Centre for Defence Studies, told the BBC he thought it "unlikely" that the two key figures would be in the same place at the same time.
But he said the capture of Qusay - the "heir apparent" - to Saddam Hussein, would be "absolutely critical".
US forces have so far announced the capture of 34 of the 55 Iraqis on the most-wanted list of members of the ousted regime.