BAGHDAD -- A suicide bomber detonated his explosives in a crowded coffee shop late Friday in the northern Iraqi city of Kirkuk, killing at least 38 and wounding more than two dozen in the latest in a string of bloody attacks pounding Iraq since the start of the holy month of Ramadan this week.

Iraq is being rocked by its deadliest and most sustained wave of bloodshed in half a decade. More than 2,600 people have been killed since the start of April, raising fears that the country is once again edging toward the brink of civil war a decade after Saddam Hussein was toppled in the U.S.-led invasion.

Another suicide bomber and a shooting elsewhere in the country killed five members of the security forces, bringing Friday's toll to 43.

The late-night blast ripped through the Classico Cafe in Kirkuk, 290 kilometers (180 miles) north of Baghdad, as patrons were enjoying tea and water pipes hours after the sunset meal that breaks the daylong Ramadan fast, police officials said.

The city is a flashpoint for ethnic tensions, with its mix of Arabs, Kurds and Turkomen holding competing claims to claims for control of the oil-rich area. The Kurds want to incorporate it into their self-ruled region in Iraq's north, but Arabs and Turkomen are opposed.

There has been no claim of responsibility for the Kirkuk blast or other attacks in recent days. But Sunni extremists, including al-Qaida's Iraq branch, frequently targets Shiites, security forces and civil servants in an effort to undermine the Shiite-led government in Baghdad. They also are believed to be behind frequent attacks in a band of disputed territories around Kirkuk aimed at heightening ethnic tensions in the area.

The cafe attack wounded 26, police and hospital officials said. All officials spoke on condition of anonymity as they were not authorized to talk to journalists.

Hours before the Kirkuk attack, Sunni cleric Salah al-Nuaimi urged calm among Iraqis during a joint Sunni-Shiite sermon Friday in Baghdad aimed at easing sectarian tensions.

"Enough is enough," al-Nuaimi told worshippers at a Baghdad mosque. "We all love Iraq, we are all Iraqis and we want to be united. We want to stop the bloodletting, and develop and build Iraq."

Earlier in the day, a suicide car bomber struck a police patrol outside the northern city of Mosul, killing four policemen, a police officer and a medical official said. Mosul is 360 kilometers (225 miles) northwest of the Iraqi capital.

And outside the northern city of Tikrit, 130 kilometers (80 miles) north of Baghdad, drive-by shooters armed with pistols fitted with silencers killed a senior police officer. The attack took place in the town Shirqat, a police officer said.

Officials also provided details of new attacks on Iraqi Shiites late the previous night.

In one of the attacks on Shiites, a suicide bomber rammed his explosives-laden motorcycle into a funeral tent for a Shiite family in the town of in Muqdadiyah, about 90 kilometers (60 miles) north of Baghdad, officials said. The late Thursday evening explosion killed 13 people and wounded 24, the officials said.

In the northern town of Dujail, about 80 kilometers (50 miles) from Baghdad, a parked car bomb went off outside a Shiite mosque late on Thursday. As people gathered around the blast site, another bomb went off. That twin bombing killed at least 11 people and wounded 25, mayor Nayif al-Khazrachi said. Two medical officials, who weren't authorized to speak publicly, confirmed the casualty figures.

The two attacks raised the overall death toll Thursday from a series of attacks, which included assaults on police stations in the cities of Ramadi and Fallujah west of Baghdad, to 40.

On Wednesday, gunmen launched an assault on an army checkpoint and special oil industry police assigned to protect a nearby pipeline in the western Iraqi desert, killing at least 14 troops there.