The polling began at 7:00 a.m. (0400 GMT) to usher in a new course of the oil-rich but violence-shattered country. Shortly after the polls began, explosions echoed in several parts of the country.

In Baghdad's Shiite slum of Sadr City, a mortar struck a voting center and killed at least four voters, police said.

Meanwhile, one suicide bomber detonated his explosive-filled belt at the entrance of a voting station in al-Zahawi school in western Baghdad.

"The blast killed one policeman and wounded four others," Colonel Adnan Abdul-Rahman told Xinhua.

In Baquba, about 50 km northeast of Baghdad, explosions were heard as voters went for the poll. To the south, a bomb exploded at a polling station in central Basra, a mainly Shiite city.

The 275-seat National Assembly will be formed by proportional representation of votes with a one-year mandate. It will choose a transitional government and draft a permanent constitution put for a national referendum by Oct. 15.

A new government and parliament will then be elected through another ballot by the end of this year under the guidance of the constitution.

As of Friday, over 280,000 Iraqi expatriates have begun to cast their votes.

Hailing the voting, Interim Iraqi President Ghazi Mashal Ajil al-Yawar and interim Prime Minister Iyad Allawi called on Iraqis to practise their rights.

"Thank God, Thank God. Blessed are the Iraqi elections. We greet all Iraqi people and urge them not to give up their rights, to vote for Iraq, elect Iraq and not to give up on Iraq," Yawar told reporters shortly after casting his ballot.

"I am your brother and the father of younger generations ... it is your duty to elect Iraq," he said.

Allawi, for his part, said, "This is the start of a new era, for the first time, Iraqis are deciding on their own future and defying the terrorist forces."

The Iraqi government has taken security measures to safeguard Sunday's election. Land borders have been closed as of Friday and travel between provinces inside the country is also banned. An extended curfew has been announced in most cities from 7 p.m. to 6 a.m. (1600 to 0300 GMT).

However, some Iraqis have been afraid of being attacked when or after they voted. Indelible blue ink that will be daubed on their index fingers to prevent repeated voting could mark them for death.

Insurgent groups have vowed to derail the elections and kill anyone who dares to vote.

"For the last time, we warn that (Sunday) will be bloody for the Christians and Jews and their mercenaries and whoever takes part in the (election) game of America and Allawi," said a statement by the group of Jordanian-born militant Abu Musab al-Zarqawi.