BAGHDAD,(AP)- Iraq”s president called for national unity on Thursday as mortar attacks killed four civilians in the northern city of Mosul and police opened fire on demonstrators in Saddam Hussein”s hometown Tikrit, wounding four.

There was no word on the fate of kidnapped Egyptian envoy Ihab al-Sherif since al-Qaeda”s branch in Iraq threatened to kill him in a Web posting Wednesday. Iraqi officials called on other countries to stay on course and keep their diplomats here despite a campaign to isolate Iraq”s U.S-backed government among its Muslim and Arab neighbors.

President Jalal Talabani addressed hundreds of Shiite clerics on Thursday at a constitutional conference in the Shiite holy city of Najaf, about 160 kilometers south of Baghdad. &#34Drafting the constitution, God-willing, will be done on schedule and I am confident about cooperation between Shiite and Kurdish legislators to do the job&#34, Talabani said.

Talabani, a longtime Kurdish leader, added that all Iraqis will participate in drafting the constitution including representatives from the Sunni Arab community, whose members boycotted January”s general elections and now make up the core of the violent insurgency.

A parliamentary committee writing Iraq”s new charter should finish the draft by Aug. 15 so it can be ready for a referendum two months later. A new constitution must be ratified before elections in December.

In fresh violence, mortar attacks aimed at a police station killed four civilians and wounded up to 46 more after striking surrounding streets in Mosul, the U.S. military said.

Elsewhere, police opened fire on 1,000 demonstrators at the seat of the provincial government in Tikrit as they were protesting the killing of the local council”s head official, authorities said. At least four were wounded.

The protesters demanded the resignation of the deputy governor and police chief because they believe their clan was responsible for Wednesday”s killing of Ali Ghalib Ibrahim, who belongs to a rival clan, Mayor Wael Ibrahim Ali said.

Ibrahim, who headed Salahuddin”s provincial council, was killed while driving in Tikrit, the province”s capital, 130 kilometers north of Baghdad. &#34He was fighting the corruption in the city council and that”s why they assassinated him,&#34 Ali said during the demonstration.

Police guarding the provincial government building first fired warning shots into the air followed by volleys into the crowd, police Lt. Khudhir Ali said. The four wounded including a policemen, but it was not clear how he was shot, he said.

A new terror command announced this week purportedly by Abu Musab al-Zarqawi, to target a Shiite militia claimed responsibility for its first operation on Thursday, the killing of a Shiite in south Baghdad. &#34Your brothers in the Omar Corps, which belongs to the al-Qaeda in Iraq, on Wednesday assassinated a leading member in the corps of treason, the Badr Corps in Doura,&#34 a statement posted on an al-Qaeda-linked web site said.

Police confirmed that a member of the Badr Brigade, led by the Supreme Council for the Islamic Revolution in Iraq, was killed on Wednesday in the Doura district in southern Baghdad.

In an audiotape found Wednesday on the same Web site, a speaker claiming to be al-Zarqawi announced formation of the Omar Corps to &#34eradicate&#34 the Badr Brigade.

Al-Zarqawi”s group has been targeting Shiites, who dominate Iraq”s government, in a bid to trigger civil war.

In Baghdad, three attacks on diplomats in four days prompted some Arab and Muslim governments to raise questions about security as a condition for upgrading ties to the new Iraqi government, as the United States wants.

The threat to kill Egyptian envoy al-Sherif, seized by gunmen in western Baghdad on Saturday, marks a dramatic escalation in a campaign to isolate Iraq diplomatically in the Arab and Muslim worlds. On Tuesday, gunmen fired on senior envoys from Bahrain and Pakistan in apparent kidnap attempts.

The threat on al-Sherif”s life came in a statement on a web site linked to al-Qaeda.

Separately, five decapitated bodies were found Thursday on a road in north western Iraq, police said. The bodies were dressed in civilian clothes and found on the road between Rawah and Ramadi, police Maj. Hashim Mohammed said.

Rawah is located 210 kilometers northwest of Ramadi, the capital of rebel-infested Anbar province.

More than 1,465 people have been killed in insurgent attacks since Prime Minister Ibrahim al-Jaafari announced his new Shiite-led government on April 28.

Iraqi security forces, however, have made significant progress in reducing violence in the capital since Operation Lighting was launched in May to combat insurgent groups in Baghdad, the Interior Ministry said.

Nearly 1,000 terror suspects have been arrested in the past two months, including four Sudanese, three Palestinians, two Egyptians, two Jordanians and one Syrian, the ministry said.

Officials also there were 10 car bomb attacks in Baghdad last month compared to 70 in May and attributed the decrease to Operation Lightning.