BAGHDAD (Reuters) - Iraq’s parliament on Thursday approved a security pact with the United States that paves the way for U.S. forces to withdraw by the end of 2011, taking the country a big step closer to full sovereignty.

The deal, which parliament linked to a series of promised political reforms and a public referendum next year, brings in sight the end of a U.S. military presence that began with the 2003 invasion and ouster of dictator Saddam Hussein.

It will test whether Iraqi police and soldiers are ready to handle security after years of bloodshed between majority Shi’ites and Sunni Arabs who were initially allied with al Qaeda fighters battling U.S. forces.

The pact replaces an expiring U.N. mandate. It gives Iraq authority over about 150,000 U.S. troops in the country, who will be obliged to withdraw from towns by mid-2009, and makes them liable for some crimes committed when they are off duty.

“It is a historic day for the great Iraqi nation. We have made real one of its most important achievements,” Prime Minister Nuri al-Maliki said in an address to the nation.

Lawmakers in Iraq’s 275 seat parliament passed the deal with 149 MPs out of 198 present voting for it. The pact consists of a Status of Forces Agreement and a long-term strategic framework agreement, which defines U.S.-Iraqi ties for years to come.

Several hours after it was signed a suicide car bomber killed four people, including two policemen, and wounded 41 others in the northern Iraqi city of Mosul, police said.

Though the deal stipulates an end-2011 U.S. troop withdrawal deadline, Iraq was hopeful its forces would grow capable enough to take full responsibility on their own before then.

“The withdrawal, theoretically, is completed at the end of December 2011, but we are expectant and hopeful that we could achieve that earlier,” government spokesman Ali al-Dabbagh said.

Agreeing the departure date was seen by Iraq as clinching a key concession after months of arduous talks with Washington negotiators initially loathe to specify a withdrawal timetable.

“It affirms the growth of Iraq’s democracy and increasing ability to secure itself,” a statement from outgoing U.S. President George W. Bush said of parliament’s vote.

ACRIMONIOUS NEGOTIATIONS

The vote had been postponed from Wednesday due to acrimonious negotiations over demands from Sunni Arabs, who were dominant under Saddam, for concessions largely unrelated to the pact.

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Iraq’s influential top Shi’ite cleric Grand Ayatollah Ali al-Sistani had called for consensus from all of the communities, making it important for the government to seek the inclusion of Sunni Arabs.

In the end, Iraq’s Shi’ite-led coalition and Kurdish partners agreed to link the pact to the referendum and a package of reforms, such as speeding up the release of mainly Sunni detainees captured by the United States at the height of the sectarian violence.

The agreement was opposed to the last by lawmakers loyal to firebrand Shi’ite cleric Moqtada al-Sadr, who want an immediate U.S. withdrawal. They held up banners and loudly chanted, “No, no to the pact. Yes, yes to Iraq,” as parliament voted.

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The referendum is scheduled to be held by the end of July next year, Iraqi officials said.

Washington has similar pacts with several other countries.

It is expected to boost Maliki’s prestige, by allowing him to continue to call on U.S. military help while taking credit for their eventual withdrawal.

Ratification by Iraq’s president and two vice presidents is expected to be formality.