BAGHDAD, Iraq - Insurgents launched multiple attacks on Iraqi police across the dangerous Sunni Triangle today, killing 24 people - including 19 policemen - a day after the major Sunni Muslim political party pulled out of the Jan. 30 elections, citing the deteriorating security situation.

Also today, a militant group claimed to have executed eight Iraqi employees of the Sandi Group, an American security company, saying they had supported the U.S.-led occupation.

Twelve policemen died when gunmen attacked a station 12 miles south of Tikrit, Saddam Hussein's hometown, said Arkan Mohammed, a local government official.

A car bomb killed five Iraqi National Guardsmen and injured 26 near Baqouba, a town 35 miles northeast of Baghdad, after the paramilitary troops had cordoned off an area in order to disarm a roadside bomb, said Maj. Neal O'Brien.

In Baqouba itself, unidentified gunmen assassinated Capt. Na'em Muhanad Abdullah, a local police commander, and wounded three other men, a spokesman said.

Elsewhere today, a car bomb exploded in the village of Muradiya, 18 miles northeast of Baghdad, killing five civilians and wounding dozens, said Dr. Ahmed Fouad of the Baqouba General Hospital.

In Mosul, 225 miles northwest of Baghdad, a gunman attacked a police station in the northeastern Hadbaa district, said police Capt. Ahmed Khalil. One policeman died in the attack.

In another blow to plans to hold the ballot as scheduled, the largest Sunni political group withdrew from the race Monday, only hours after a suicide car bomber killed 15 people in Baghdad in an attempt to assassinate the head of Iraq's strongest Shiite party.

The rebels' campaign to disrupt the elections for a new constitutional assembly has steadily escalated in recent weeks, and most Sunni parties and religious groups have already decided to boycott the ballot, calling for a postponement of the vote until the security situation stabilizes.

Insurgents have mainly targeted members of the interim government's security forces - whom they consider to be collaborators with the American occupation forces - killing hundreds in the past two months.

The 10 employees of Sandi Group were kidnapped west of Baghdad on Dec. 13 by militants claiming to represent the Mujahedeen Army, The Black Banner Brigade, and the Mutassim Bellah Brigade.

"Eight have been executed because it was proven that they were supporting the occupying army," a man read. The other two will be release for lack of evidence," a statement said.

In the central city of Samarra a suicide attacker detonated his car in the city center wounding 10 people, including three children, police Maj. Saadoun Ahmed Matroud.

Shortly after the explosion, people were told through mosque loud speakers to stay indoors because of a curfew, and U.S. and Iraq troops set up roadblocks, witnesses said.

Several mortar rounds targeted an Iraqi police station in Mufriq, north of Baghdad, injuring three policemen, said Lt. Saleh Hussein. The three were hospitalized.

Meanwhile, in an audiotape broadcast Monday by the Al-Jazeera satellite television, a man purported to be Osama bin Laden endorsed Jordanian militant Abu Musab al-Zarqawi as his deputy in Iraq and called for a boycott of the elections.

In urging a boycott of the election, the voice on the Al-Jazeera tape described al-Zarqawi as the "emir" of al-Qaida in Iraq and called on Muslims there "to listen to him." Last month al-Zarqawi declared allegiance to bin Laden and changed the name of his group, which is responsible for numerous car bombings and beheadings of foreign hostages in Iraq, to Al-Qaida in Iraq.

Shiites comprise by far the biggest community in Iraq, with Sunni Arabs and ethnic Kurds making up 20 percent each. Many people in Iraq and abroad fear the legitimacy of the upcoming election will be brought into question if Sunnis refrain from voting.