The U.S. Embassy in Baghdad has been hit in an apparent rocket or mortar attack, and U.S. officials confirm two Americans have been killed and at least four others wounded.

Initial reports say indirect fire hit the south side of the embassy, killing a civilian and a member of the military.

The embassy is housed in Saddam Hussein's former Republican Palace, inside the heavily guarded Green Zone.

The attack comes just hours before Iraqis are to go to the polls for the first free elections in nearly 50 years.

Interim Iraqi Prime Minister Iyad Allawi has called on Iraqis to vote in Sunday's historic elections, despite unrelenting violence that has claimed the lives of at least 20 more people  Saturday.

In an interview with British television channel, SkyNews, Mr. Allawi said Iraqis should not let the insurgents stop them from deciding their future.

Earlier, interim President Ghazi al-Yawar said he expects fears of violence will deter most of the 14 million eligible Iraqis from going to the polls. Pre-election violence Saturday has killed at least 17 Iraqis and three Americans.

The country is virtually locked down for the vote, with borders closed, traffic banned and extended curfews in effect. The government said Saturday it will extend emergency laws in all areas except the semi-autonomous Kurdish north for another month, empowering itself to continue such measures.

But the violence has not stopped election workers from delivering ballots and ballot boxes to polling centers, and officials say preparations are moving forward.

Meanwhile, some 85,000 Iraqis living abroad already have cast their ballots for the new government. Expatriate voting began Friday and will continue through Sunday at voting centers in 14 countries from Australia to Europe to the United States.

Some information for this report provided by AP and Reuters.