Iraqi politicians struggled Saturday to reach agreement on candidates for two key security posts that remained vacant a week after Prime Minister Nouri al-Maliki's government of national unity took office.

The political maneuvering came as Iran's foreign minister visited the Shiite holy cities of Karbala and Najaf, where he met with Iraq's top Shiite cleric Grand Ayatollah Ali al-Sistani as he wrapped up the second high-level visit by an Iranian delegation since Saddam Hussein was ousted in April 2003.

Iranian Foreign Minister Manouchehr Mottaki met with al-Maliki and other top Iraqi officials on Friday, and he rejected a U.S. offer of direct talks on Iraq as Tehran hardened its position against international pressure to stop uranium enrichment.

Mottaki also got a boost from his Iraqi counterpart, Hoshyar Zebari, who said Iran has the right to peaceful nuclear research — a stance that runs counter to U.S. efforts to force Tehran to stop all nuclear activities amid fears it is seeking to develop atomic weapons.

CountryWatch: Iraq

Al-Maliki said Thursday that he could be ready soon to name the two men who will be charged with carrying out his pledge to take over security for Iraq within 18 months, but Friday passed without word of the appointments.

His spokesman, Yassin Majid, said the main Shiite, Sunni and Kurdish political blocs in the 275-member parliament would resume talks on the candidates Saturday afternoon "and probably this issue will be settled today."

Al-Maliki left the posts vacant when he formed his government last week because of ethnic and sectarian disagreements. He said earlier this week that problems included the large number of candidates presented by his Shiite United Iraqi Alliance and the Sunni Arabs' Iraqi Accordance Front and concerns about links of some nominees to the former regime.

Violence resumed Saturday as a bomb in a parked car exploded near a busy bus station in southern Baghdad, killing at least four civilians and wounding seven, police Capt. Jamil Hussein said.

Gunmen also broke into a gardening store in Baghdad and killed the Shiite owner, Ali Hussein Kadhin, a Shiite, police Lt. Maitham Abdul Razzaq said.

Both attacks occurred in the predominantly Sunni neighborhood of Dora, and came a day after bombs hit three different outdoor markets in largely Shiite areas of the capital, killing at least 18 people and wounding more than 60.

The U.S. military, meanwhile, said six terror suspects had been captured Friday in Ramadi, saying information from recent detainees led to the raid.

Residents in the volatile city, 115 kilometers (70 miles) west of Baghdad complained they had been surrounded for days without water or electricity amid recent clashes between U.S. forces and insurgents. Footage from AP Television News showed collapsed tin stalls and rubble as a fighter plane flew overhead and gunfire could be heard.

Elsewhere, a policeman was killed and an officer wounded when a roadside bomb exploded near their convoy in Baghdad's western district of Mansour, Razzaq said. He also said three policemen were wounded when gunmen ambushed a convoy of Interior Ministry commandos in the southern neighborhood of al-Bayaa in the capital.

Gunmen in three speeding cars also ambushed a patrol in western Baghdad, wounding 10 people, including six policemen, and two other policemen were injured in drive-by shootings in a nearby neighborhood, police Capt. Jamil Hussein said.

Two other policemen were injured Saturday in drive-by shootings elsewhere in western Baghdad, when gunmen in two speeding cars attacked their patrol in Amiriya neighborhood of western Baghdad, police Capt. Jamil Hussien said.

Late Friday, a melee broke out during a soccer game at a stadium in Baghdad after a referee rejected a goal, leaving two people killed and four injured, Capt. Mohammed Abdul Gheni of Risafa police said.

An Iraqi contractor with the U.S. also was killed in Basra Friday afternoon, police Capt. Mushtaq Kadhim said.

Also Friday, Italy announced it would pull 1,100 of its troops from the U.S.-led coalition in June, the first specific numbers about its planned withdrawal. The country has some 2,700 troops in Iraq, mostly in the southern city of Nasiriyah.

Deputies close to the negotiations on the defense and interior ministry posts had said it was doubtful a decision would be made by Saturday, although at least one Shiite appeared to be edging toward getting the interior minister portfolio — former National Security Adviser Mouwafak al-Rubaie, a 57-year-old Shiite.

Hashim al-Taie, a Sunni legislator involved the negotiations, complained nominees had been rejected by the dominant parties because they were former Baath Party members.

"This issue became a thorny one," he told The Associated Press. "We have not agreed on a specific names and we hope that this issue to be settled in today's meeting."

"Now, we have three candidates; two are independent and the third is from the National Accordance Front," he added. "They all former army officers but there were not Baath party members."

The Iranians and the U.S. had expressed willingness earlier this year to hold meetings on how to stabilize Iraq.

But Mottaki, speaking at a news conference Friday with Iraqi Foreign Minister Hoshyar Zebari, said Iran had changed its mind.

"Unfortunately, the American side tried to use this decision as a propaganda and they raised some other issues. They tried to create a negative atmosphere," he said.

The foreign minister later said Iran would strike back against any U.S. attack. "In case the Americans attack Iran anywhere, Iran will respond to the attack," he said.

Zebari said the Iraqis wanted a Middle East safe from weapons of mass destruction, but he stressed Iran's right to develop nuclear energy.

"We believe that Iran has the right to research in nuclear power for peaceful purposes," he said.