BAGHDAD – Suicide bombers in a crowded Baghdad commercial district and Saddam Hussein’s hometown of Tikrit killed as many as 33 people Sunday as insurgents tried to turn a monthslong deadlock over forming a new Iraqi government to their advantage.

The latest violence began when bombers drove two cars packed with nearly 180 pounds of ammonium nitrate toward the gates of the Trade Bank of Iraq building in Baghdad and detonated the explosives after striking the surrounding blast walls.

Iraqi military spokesman Maj. Gen. Qassim al-Moussawi said at least 18 people were killed and 42 wounded.

But three Iraqi police officials and a doctor at the Yarmouk hospital where many victims were taken put the toll at 28 killed and 57 wounded. Conflicting casualty tolls are common in the chaotic aftermath of bombings in Iraq.

Hours later, a man wearing an explosives vest blew himself up as police and onlookers responded to a roadside bomb apparently set as a trap in the northern city of Tikrit. At least five people were killed and 12 wounded in the late-night attack, according to police and hospital officials.

The attacks added weight to warnings that insurgents would try to foment unrest as politicians squabble over forming a new government more than three months after inconclusive national elections.

The explosions capped a week in which about 100 people were killed in bombings and shootings nationwide, including at least 26 who died in a commando-style assault against the central bank in Baghdad last Sunday.

An al-Qaida in Iraq front group, the Islamic State of Iraq, claimed responsibility for that attack, saying it targeted the institution responsible for funneling “oil money and the stolen wealth of Muslims” to the West.