BAGHDAD - US President George W. Bush made a surprise farewell visit to Baghdad on Sunday, five weeks before he hands over the tricky task of overseeing the withdrawal from Iraq to his successor Barack Obama.

Bush met his Iraqi counterpart Jalal Talabani at the start of his fourth visit since US-led troops toppled Saddam Hussein's regime in April 2003 during a deeply unpopular war.

His visit comes hot on the heels of a trip to Iraq on Saturday by US Defence Secretary Robert Gates, who said that the US mission in the country was in its "endgame."

Iraq's parliament in November approved -- after months of intense political wrangling -- the Status of Forces Agreement which also sets June 30 as the deadline for the pullout of combat forces from cities and villages.

The pact will govern the presence of 146,000 US troops stationed in more than 400 bases when their UN mandate expires at the end of the year, giving the Iraqi government veto power over virtually all of their operations.

Gates, who president-elect Obama has picked to stay on at the Pentagon when he moves into the White House on January 20, told US troops on Saturday: "We are in the process of the drawdown."

"We are, I believe, in terms of the American commitment, in the endgame here in Iraq."

The top US commander in Iraq, General Raymond Odierno, who met with Gates, said on Saturday that US troops would stay in Iraqi cities in a support and training role even after the June target date for their withdrawal.

As part of political bargaining leading up to the vote, the Baghdad government agreed to demands by Sunni parties to hold a referendum on the accord no later than July 30.

In Iraq, Bush is also set to meet Talabani's two vice presidents, parliament speaker Mahmud Mashhadani, the president of the northern Kurdish goverment Massud Barzani and Abdul Aziz al-Hakim, leader of Supreme Islamic Iraqi Council, one of the most powerful Shiite factions.

The Shiite radical movement of Moqtada Sadr, which strongly opposed the security agreement, said Odierno's remarks on the support troops showed that Washington had no intention of sticking by any of the deadlines.

"As we predicted, the comments fly in the face of the security agreement," the head of the movement's political bureau, Liwaa Sumeissim, told AFP on Sunday just a few hours before Bush's arrival.

"When we rejected the agreement, we did so because we were totally convinced that the US side would never feel bound by it, particularly when it conflicted with motives that brought them here.

Obama has said he favours "a responsible withdrawal from Iraq" within 16 months after taking office.

While the security situation in Baghdad and other parts of the country has significantly improved, violence remains a major factor in Iraq's everyday life.

More than 4,200 US troops and tens of thousands of Iraqi soldiers have been killed in the country since the invasion.

Problems continue to dog the massive economic reconstruction programme undertaken since the 2003 invasion.

The New York Times reported on Sunday that an unpublished US government report had found that US-led efforts to rebuild Iraq were crippled by bureaucratic turf wars, violence and ignorance of the basic elements of Iraqi society, resulting in a 100-billion-dollar failure.

It cited a 513-page federal history of the reconstruction effort circulating in Washington in draft form among a tight circle of technical reviewers, policy experts and senior officials.

By mid-2008, the document said, 117 billion dollars had been spent on the reconstruction of Iraq, including about 50 billion in US taxpayer money, the paper noted, the Times.