Prime Minister Nouri al-Maliki pledged Tuesday to push ahead with efforts to curb rampant sectarian and militia violence after a series of brazen attacks, including the kidnappings of 50 people in broad daylight in Baghdad.

Police found nine severed heads in fruit boxes in a village northeast of the capital, which followed a similar grisly discovery there on Saturday.

CountryWatch: Iraq

Al-Maliki, who announced a plan last month aimed at restoring order in Baghdad, acknowledged the deteriorating security situation in the capital and other areas but did not comment on Monday's abductions.

"The parties that are against the political process have increased their bloody operations to derail and bring down the national unity government, but, God willing, they will lose," he said at a news conference.

He also said his security plan for Baghdad had been ratified and would soon be implemented, and he said another plan was in the works for volatile Diyala province.

"The security situation is complicated," he said, citing unspecified internal and foreign interference. "Yes, the mission is hard and tough, but we have short and long-term plans to fight and defeat terrorists and ensure security."

"But the government and its security forces can't deal with this security situation alone and all the people have to back the security institutions," he added.

A major Sunni Arab political party, meanwhile, accused the Interior Ministry of trying to cover up police involvement in the raid in which gunmen wearing police uniforms descended upon bus stations in central Baghdad and began randomly grabbing people, including travelers, merchants and vendors.

The Iraqi Islamic Party also appealed to Shiite and Sunni religious and political leaders to intervene directly to end the violence.

Prominent Sunni politician Adnan al-Dulaimi also appealed for the government and U.S.-led forces to take action against such attacks and urged the speedy appointment of interior and defense ministers.

"The killing operations have become a phenomena," he said. "Fifty Iraqis have been abducted and the Iraqi officials have done nothing to stop those behind these terrorist acts."

"I call on the political blocs to expedite the appointments of the interior and defense ministers," he said. "It might reassure the Iraqi people and end these barbaric acts."

The Shiite-dominated Interior Ministry, which oversees the police and has been accused of backing militias in sectarian violence, denied its forces were behind the kidnappings.

The Sunni group said it was certain that Iraqi police carried them out, although it did not provide specific evidence.

"The Iraqi police denied their involvement in this operation, despite the fact that it occurred in broad daylight ... and in central Baghdad," said party member Alaa Maki. "But we now have enough evidence to prove the involvement of the Iraqi police in this incident."

The second such mass kidnapping in less than a month was the latest in a series of setbacks for al-Maliki. The Shiite prime minister also has been frustrated in efforts to crack down on sectarian and militia violence in the oil-rich southern city of Basra, where attacks have continued despite his declaration of a state of emergency on May 31.

Al-Maliki still has not been able to reach consensus among Iraq's ethnic and sectarian parties on candidates for interior and defense ministers — posts he must fill to implement his ambitious plan to take control of security from U.S.-led forces within 18 months.

The Bush administration hopes a unity government will drain support for the Sunni-led insurgency and restore order in Baghdad and elsewhere in the country, enabling the United States to withdraw its troops.

The boxes containing the severed heads — all from men — were discovered by a highway in the village of Hadid, near Baqouba, a mixed city 35 miles northeast of Baghdad that has seen a recent rise in sectarian violence.

The heads were transferred to the city morgue and an investigation was under way, according to the Joint Cooperation Center, which is run by Iraqi and U.S. forces.

On Saturday, police found eight severed heads in the village, with a note indicating at least one of those men had been killed in retaliation for the slaying of four Shiite doctors and a former Shiite official.

A decapitated body also was found Tuesday in Aziziyah, 35 miles southeast of Baghdad.

A roadside bomb missed a U.S. military convoy in central Baghdad but killed a woman and wounded three other pedestrians, Lt. Thair Mahmoud said. The three-vehicle convoy was traveling near a busy bus station when the bomb detonated.

Three local council workers were killed in a drive-by shooting in western Baghdad. Two mortar rounds also slammed into an eastern Baghdad neighborhood, killing two bystanders and wounding nine others, Lt. Ahmed Muhammad Ali said.

The Interior Ministry, meanwhile, said two college students had been killed Monday by gunmen in Baghdad's southern Dora district, contradicting reports that 11 had been slain. The al-Yarmouk hospital also reported receiving only two bodies from a shooting. It was unclear if the victims were Sunnis or Shiites.

On Sunday, masked gunmen stopped two minivans carrying students north of Baghdad, ordered the passengers off, separated Shiites from Sunni Arabs, and killed the 21 Shiites "in the name of Islam," a witness said.

In southern Iraq, a bomb exploded near an Italian patrol Monday night, killing one Italian soldier and wounding four, Adm. Gianpaolo Di Paolo said in Rome. The military said the blast occurred about 60 miles north of Nasiriyah, where the Italians are based.