The United States on Monday handed over sovereignty to an interim Iraqi government two days earlier than expected, aiming to forestall guerrilla attacks with a secretive ceremony formally ending 14 months of occupation.
Iraq's outgoing US governor Paul Bremer handed a letter to Iraq leaders sealing the formal transfer of powers before immediately flying out of the country.
The low-key ceremony was over before it was announced and came as a surprise to ordinary Iraqis.
Its hurried and secret nature appeared to reflect fears that guerrillas could stage a spectacular attack on the scheduled date of June 30.
At a second ceremony in the afternoon - this time broadcast live on Iraqi television - the government was sworn in and Prime Minister Iyad Allawi urged all Iraqis to stand together against foreign militants wreaking havoc in the country.
"I call on our people to stand united to expel the foreign terrorists who are killing our children and destroying our country," Allawi said, in comments broadcast around the world.
At the earlier ceremony, which formally transferred sovereignty at 10:26 am (0626 GMT), President Ghazi Yawar hailed "a historic day, a happy day, a day that all Iraqis have been looking forward to".
US President George W. Bush quietly took note of the secret handover by checking his watch at a Nato summit in Istanbul and shaking hands with his closest war ally, British Prime Minister Tony Blair. The two exchanged knowing smiles and shook hands as they sat around a table listening to speeches.
Bush later hailed the handover as "a day of great hope for Iraqis" and pledged not to abandon Iraq.
US and British officials say the handover is a key step on the path to democracy in Iraq, but one of the government's first actions as a sovereign power is expected to be the imposition of emergency laws, including curfews, to crack down on guerrillas.
Allawi said after the handover that he was committed to holding elections in January as scheduled. Last week he was quoted as saying insecurity might force the polls to be postponed until February or March.
Although Allawi's government will have "full sovereignty", according to a UN Security Council resolution earlier this month, there are important constraints on its powers.
It is barred from making long-term policy decisions and will not have control over more than 160,000 foreign troops who will remain in Iraq. The government has the right to ask them to leave, but has made clear it has no intention of doing so.