The top US commander in the Middle East, Gen John Abizaid, has said Iraq could move toward civil war if the sectarian violence is not stopped.
Gen Abizaid's warning was backed up by Gen Peter Pace (left)
"Sectarian violence is probably as bad as I have seen it," Gen Abizaid told the Senate Armed Services Committee.
A similar warning was contained in a confidential memo to UK Prime Minister Tony Blair by the UK's outgoing ambassador to Iraq.
William Patey also predicted the break-up of Iraq along ethnic lines.
A bomb left near a busy Baghdad shopping area on Thursday killed at least 10 people and injured 29, police said.
US commanders have recently moved 3,700 troops from Mosul to Baghdad to bolster the capital's fragile security.
Love not hate
Gen Abizaid told the committee the top priority was to secure the Iraqi capital, where the struggle was at a "decisive" stage. "It is clear that the operational and tactical situation in Baghdad is such that it requires additional security forces, both US and Iraqi," he said.
But Gen Abizaid also said he remained optimistic that the Iraqi government and iraqi forces, with US support, could prevent the slide into civil war.
Gen Abizaid's warning was backed up by Gen Peter Pace, Chairman of the Joint Chiefs of Staff, who said ultimately descending into or avoiding civil war depended on the Iraqis.
"Shia and Sunni are going to have to love their children more than they hate each other," Gen Pace said.
The two generals were joined by US Defence Secretary Donald Rumsfeld who did not comment directly on the prospect of civil war but again warned against pulling out US troops prematurely.
British Ambassador William Patey, who left Baghdad last week, gave a bleak assessment of Iraq's future in his final diplomatic cable.
"The prospect of a low intensity civil war and a de facto division of Iraq is probably more likely at this stage than a successful and substantial transition to a stable democracy."
He said that position was not hopeless but it would be "messy" for five to 10 years.