Up to 30 people were killed and scores more injured when a suicide bomber blew himself up among the luncheon gathering of a tribal leader south of Baghdad today after sneaking in through the backdoor of the venue.

The attack came a day after Nouri al-Maliki, the Iraqi Prime Minister, hailed Iraq’s renewed sovereignty as all US forces in the country came under its authority.

Blood and body parts splattered the walls of a reception hall adjacent to the house of Sheikh Mohammed Abdullah Salih, leader of the Sunni al-Qaraghouli tribe, following the blast in the once-restive town of Yousifiya.

An Interior Ministry source put the death toll at 30, with 110 wounded. Colonel Aman Mansour Ibrahim, who was on the scene, however, said 24 were killed and 38 injured. The US military said Iraqis were reporting 23 dead and 32 wounded.

Varying tolls are common in the immediate aftermath of a bombing in Iraq.

A man standing a few yards from the entrance to the hall described the carnage after the bomber, believed to have been a member of the tribe, struck.

“What an aftermath we saw — shattered glasses mixed with blood, everybody on the ground, a bad smell, blood, remains of bodies stuck to the wall,” Ismael Abu Ayab al-Qaraghouli told the Associated Press.

The host, who was slightly injured in the blast, had invited senior tribal figures to lunch along with members of the Sons of Iraq, former Sunni insurgents who turned against al-Qaeda under the payroll of the US military. The Iraqi Government is increasingly taking over responsibility for their salaries.

The bomber was a suspected member of al-Qaeda, according to a police official. Suicide vests are often used by the Sunni Islamist extremist group in Iraq.

The attack is the deadliest since a restaurant bombing in the north of the country on December 11 in which at least 55 people were killed and 95 wounded.

It underscores the ongoing challenges for Iraq’s police, army and politicians as the US military takes a more backseat role under a security agreement between Baghdad and Washington that came into force on New Year’s Day, replacing a UN Security Council resolution that expired at the end of 2008.

Under the terms, US forces are due to pull out of cities and towns by the middle of the year and leave Iraq by the end of 2011.

In a gesture of the power shift, the presidential palace of Saddam Hussein in Baghdad, once the seat of the US occupation, was handed to the Iraqi Government along with control for security in the surrounding green zone.

Entering the fortified zone today, however, The Times saw little sign of any immediate change on the ground, with the same US and Iraqi soldiers manning the entrance used. The palace car park, however, was empty on one side of the hundreds of SUVs, cars and Humvees that used to fill the space.

US troops are also still firing their weapons on the street, albeit on joint missions with Iraqi forces.

An Iraqi woman was shot and wounded by US soldiers in central Baghdad yesterday after she acted suspiciously and failed to respond to warnings, the military said today. “Concerned by the danger she might present to the security forces and civilians, given her repeated failure to respond to warnings, MND-B Soldiers fired two rounds, wounding the woman,” it said in a statement.

US and Iraqi forces are on alert for female suicide bombers after a sharp rise in such attacks over the past year.

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