BAGHDAD - Insurgents killed at least 24 people in motorcycle and car bomb attacks on Thursday, one targeting the bodyguards of Iraq's Kurdish deputy prime minister and another killing a deputy provincial governor.

In the northern town of Tuz Khurmatu, on the highway between Baghdad and the strategic oil city of Kirkuk, a suicide bomber plowed his car into a restaurant where bodyguards of Deputy Prime Minister Rowsch Shways were eating, police said.

Doctors said 12 people were killed and 37 wounded.

The Army of Ansar al-Sunna, one of Iraq's most feared insurgent groups, claimed responsibility for the attack in an Internet statement.

In another suicide attack, an insurgent blew up his car among a convoy of local government vehicles in the town of Baquba, killing five people including the deputy head of the provincial government, Hussein Alwan al-Tamimi, police said.

Al Qaeda's network in Iraq said it carried out the attack.

A third suicide bomber struck in Kirkuk, detonating his car as U.S. diplomatic vehicles entered the North Oil Company, a state firm that manages pipelines and refineries in oil-rich northern Iraq. Police said two people were killed and 12 hurt.

And in the northern city of Mosul, two motorcycles strapped with explosives blew up outside a coffee shop frequented by police, killing five people and wounding 13, police said.

Two days ago, gunmen in three cars opened fire on shops in northern Baghdad killing nine civilians, Iraq's Defense Ministry said on Thursday, saying it knew of no motive for the attack.

Since a new Shi'ite Islamist-led cabinet was announced in late April there has been a sharp escalation in violence, with the number of suicide bombings and shootings soaring.

More than 700 Iraqis and 78 U.S. soldiers were killed in May, making it the deadliest month in Iraq since January.

In Tuz Khurmatu there have been three suicide bomb attacks in the past 10 days. Police said two of the dead and eight of the wounded from Thursday's blast were Shways's bodyguards.

Zarqawi Defiant

Al Qaeda's network in Iraq, led by Jordanian militant Abu Musab al-Zarqawi, has claimed responsibility for many of the deadliest attacks in Iraq. In an Internet statement last month, al Qaeda said Zarqawi had been wounded.

But an audio message purportedly from Zarqawi posted on the Internet earlier this week assured al Qaeda leader
Osama bin Laden that his wounds were not serious and he was still in Iraq directing insurgent attacks.

A U.S. intelligence official said the audio recording appeared to be authentic.

Air Force Gen. Richard Myers, chairman of the U.S. Joint Chiefs of Staff, said on Wednesday the
Pentagon believed Zarqawi had been wounded, but did not know how severely.

Defense Secretary Donald Rumsfeld warned neighboring countries not to give Zarqawi shelter.

"The current assumption is that he's in Iraq," he said. "Were a neighboring country to take him in and provide medical assistance or haven for him, they ... would be associating themselves with a major linkage in the al Qaeda network and a person who has a great deal of blood on his hands."

The U.S. military is offering $25 million for information leading to Zarqawi's death or capture.

On Wednesday, a U.S. soldier was killed by a roadside bomb, and another was killed by small arms fire, both near the city of Ramadi in western Iraq, the military said.

Since the invasion in March 2003, at least 1,660 American military and Pentagon personnel have lost their lives in Iraq.

On Sunday, the government said it had launched Operation Lightning, a major crackdown on insurgents in Baghdad.

Ministers said the operation would involve 40,000 Iraqi police and soldiers who would search Baghdad district by district. But so far the operation has been on a much smaller scale, with Iraqi soldiers searching houses in some areas but much of the capital unaffected.

Iraqi officials said they had rounded up more than 400 suspects, but it was unclear how many were insurgents.

In western Anbar province, the heart of the insurgency, Iraqi forces said they had detained 59 wanted people in the past three days. They provided no further details.

Additional reporting by Aref Mohammed in Kirkuk and Faris al-Mehdawi in Baquba