BAGHDAD (Reuters) – Iraq’s government on Sunday renewed its pledge to crack down on militants after a massive suicide truck bomb killed 135 people in a mainly Shi’ite area of Baghdad.

Saturday’s attack was the deadliest single bombing since the U.S.-led invasion in 2003. It shocked even Iraqis accustomed to the relentless violence that threatens to plunge the country into full-scale sectarian civil war.

In fresh violence, a series of bomb attacks and drive-by shootings killed 16 people in Baghdad on Sunday, police and residents said.

Around 1,000 people have been killed across Iraq in the past week in suicide bombings, shootings and fighting between security forces and militants, according to figures compiled by Reuters from official sources.

“What did we do?” said one elderly man as he wailed in front of gutted shop fronts and homes in the Sadriya market on Sunday.

Rescue workers picked through blood-stained rubble looking for more bodies. A bulldozer was called in to clear debris from what was left of two and three-storey buildings.

Shi’ite Prime Minister Nuri al-Maliki blamed the blast on Saddam Hussein supporters and other Sunni militants.

“The government is determined to get rid of the terrorists and the outlaws. Yesterday’s bombing is just more evidence of their evil,” a senior government source said.

Maliki’s office, referring to militants, said in a statement late on Saturday that the government would “cut off their roots, their sources and their supporters.”

The prime minister vowed in January to launch a crackdown in the capital to crush insurgents who have defied attempts by his government to get control of security, but it has not yet begun.

Similar campaigns have failed in the past.

President Bush is sending 21,500 reinforcements to Iraq, most earmarked for the Baghdad offensive, despite vocal opposition at home, especially among Democrats who now control both houses of Congress.

Ordinary Iraqis are frustrated at the government’s inability to curb violence. Shi’ites in Sadriya said the Mehdi Army militia of anti-American Shi’ite cleric Moqtada al-Sadr should handle security, not government forces.

“We are fed up with the government falling short in protecting us. After four years our blood still flows,” said Abu Sajad, 37, a worker living in the Sadriya area.

The Pentagon has said the Mehdi Army poses a greater threat to peace in Iraq than Sunni Islamist al Qaeda. Sadr is a key political ally for Maliki.

More than 300 people were wounded in the Sadriya blast, caused when the bomber drove his truck, packed with one ton of explosives, into the crowded market.

An Interior Ministry source said efforts would be made to tighten control over roads leading into Baghdad, with attention paid to searching trucks.

The planned U.S.-Iraqi offensive in Baghdad is seen as a last-ditch effort to stem worsening bloodshed between minority Sunni Arabs and politically dominant majority Shi’ites.

Maliki’s critics say an offensive last summer failed because the Iraqi army committed too few troops and because he was reluctant to confront the Mehdi Army.