BAGHDAD, Iraq - A suicide driver detonated a car bomb outside the prime minister's party headquarters today, injuring at least 10 people in a blast claimed by the al-Qaida affiliate in Iraq. Authorities, meanwhile, announced the arrest of an al-Qaida figure allegedly behind the vast majority of the car bombings in Baghdad.

Leaders of a mostly Shiite Muslim faction expected to win Jan. 30's national elections said today they had no intention of establishing a cleric-ruled Islamic state in Iraq, and they vowed not to be dragged into a civil war by seeking revenge for Sunni extremist attacks.

The suicide bomber struck at a police checkpoint on the road leading to Prime Minister Ayad Allawi's Iraqi National Accord offices in central Baghdad, shaking the city center with a thunderous explosion. The wounded included eight policemen and two civilians, said Dr. Mudhar Abdul-Hussein of Yarmouk Hospital.

Al-Qaida's wing in Iraq said in a Web posting that "one of the young lions in the suicide regiment" carried out the attack against the party office of Allawi, "the agent of the Jews and the Christians."

The attacks occurred six days before Iraq's crucial national elections, the first since the fall of Saddam Hussein in 2003. Insurgents have condemned the elections and vowed to disrupt them.

In an audiotape posted Sunday on the Web, a speaker claiming to be Abu Musab al-Zarqawi declared "fierce war" on democracy and said anyone who takes part in next weekend's Iraqi elections would be considered "an infidel."

"We have declared a fierce war on this evil principle of democracy and those who follow this wrong ideology," the speaker said. "Anyone who tries to help set up this system is part of it."

The speaker warned Iraqis to be careful of "the enemy's plan to implement so-called democracy in your country." He said the Americans have engineered the election to install Shiite Muslims in power. Al-Zarqawi, who is a Sunni Arab like most of the insurgents here, has in the past branded Shiites as heretics.

The authenticity of the tape could not immediately be verified.

The Jordanian-born al-Zarqawi heads al-Qaida in Iraq, the terror network's local affiliate. The group is behind many of the car bombings, beheadings, assassinations and other attacks driving the insurgency in Iraq.

The United States has offered a $25 million reward for al-Zarqawi's capture or death - the same amount as for al-Qaida leader Osama bin Laden.

A top lieutenant of al-Zarqawi's terror group, Sami Mohammed Ali Said al-Jaaf, also known as Abu Omar al-Kurdi, was arrested during a raid in Baghdad on Jan. 15, a government statement said today.

Al-Jaaf is a suspect in 32 car bombings that killed hundreds of Iraqis, the statement said. The suspect "confessed to building approximately 75 percent of the car bombs used in attacks in Baghdad since March 2003," Allawi spokesman Thaer al-Naqib said in the statement.

Al-Jaaf was "the most lethal of Abu Musab al-Zarqawi's lieutenants," the statement said. He "claims responsibility for some of the most ruthless attacks on Iraqi police forces and police stations."

Two other militants linked to al-Zarqawi's terror group also have been arrested, authorities said - a man described as the chief of al-Zarqawi's propaganda operations and one of the group's weapons suppliers.

Al-Zarqawi has been trying to incite Sunni Muslims against the Shiite majority, playing on Sunni fears they will lose a privileged position they have enjoyed for generations.

In a news conference, politicians running on a Shiite clerical-endorsed ticket, the United Iraqi Alliance, sought to play down fears of an Iranian-style Shiite state. Hanin Mohammed Qaddou, a Sunni Muslim on the ticket, said the issue of religious government was "not part of the program and it will not be in the near future."

Alliance leaders also vowed not to seek revenge for attacks by Sunni extremists.

"We believe that we have no justifications, whether religious or political, to escalate the situation and enter into the civil war quagmire because it means the Balkanization of Iraq or the Lebanonization of Iraq," said Khudayer al-Khuzai of the Islamic Dawa Party-Iraq.

Voters are to choose a 275-member National Assembly and legislatures in each of the 18 provinces. Voters in the Kurdish-ruled area of the north will also elect a new regional parliament.

American and Iraqi officials have warned they expect rebels to unleash bloodshed and mayhem to keep voters from the polls in what supporters are advertising as the first free election in this country since the overthrow of Iraq's monarchy in 1958.

U.S. Ambassador John Negroponte acknowledged an increase in rebel intimidation of Iraqi officials and security forces and said serious security problems remain in the areas north and west of Baghdad, commonly referred to as the "Sunni Triangle."

"But security measures are being taken, by both the multinational forces here in Iraq as well as the Iraqi armed forces and police," Negroponte told "Fox News Sunday."

Three U.S. soldiers were wounded Sunday in a mortar attack in Samarra north of Baghdad, including one seriously, the U.S. command said.

On Sunday night, insurgents blew up three schools to be used as polling centers in Tikrit.

Gunmen firing from a speeding car shot dead an Iraqi police lieutenant as he was returning home Sunday night in Baghdad, an Interior Ministry official said. North of the capital, the deputy governor of Iraq's Diyala province, Ghassan al-Khadran, escaped an assassination attempt this morning as a roadside bomb struck his car.

Today, mortar rounds slammed into an Iraqi National Guard camp near Baghdad International Airport as the rumble of distant explosions reverberated through the capital. There was no report of casualties in the mortar attack.

Today's blast in Baghdad rattled buildings along the Tigris River in the center of the city and sent black smoke rising above the skyline. U.S. military helicopters cut through overcast skies above the scene.

Police fired on the car as it sped toward them, killing the driver as the blast ripped the vehicle apart, said an Interior Ministry official.

Splintered police vehicles were engulfed in flames, and gunfire rattled after the explosion.

Earlier this month, a suicide car bomber targeted the same checkpoint, killing four people and injuring 25. Police moved the roadblock of barbed wire and metal traffic barriers farther away from Allawi's office after that attack.

The site is not far from Baghdad's Green Zone, the heavily fortified compound that houses the U.S. Embassy and the offices of the Iraqi interim government. Insurgents have frequently targeted the district with mortar fire and car bombs.

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Associated Press reporter Sameer N. Yacoub contributed to this report.