BAGHDAD — Iraq’s first democratically elected government was sworn in yesterday amid escalating violence. Prime Minister Ibrahim Jaafari pledged to unite Iraq’s rival ethnic and religious factions and fight terrorism.

“You all know the heavy legacy inherited by this government. We are afflicted by corruption, lack of services, unemployment and mass graves,” Jaafari told lawmakers after taking the oath of office before the National Assembly. “I would like to tell the widows and orphans ... your sacrifices have not gone in vain.”

One by one, Jaafari and members of his Cabinet walked to a podium and pledged to serve honestly and defend Iraq and its people amid a surge of violence that has killed nearly 170 people in six days.

But five ministries — including the key defense and oil portfolios — remained in temporary hands and two deputy prime ministers’ slots were unfilled as Jaafari struggled to balance the demands of Iraq’s competing ethnic and religious factions.

Jaafari particularly wanted the defense minister’s job filled by a Sunni as a way to draw the formerly dominant minority into the fight against an insurgency that is thought to be based primarily among Sunnis.

Former Pentagon favorite Ahmad Chalabi, a Shiite and one of four deputy prime ministers, was given temporary responsibility for the key Oil Ministry.

More than two years after US-led forces drove Saddam Hussein from power, violence persisted unabated yesterday, including a gunbattle in Ramadi that killed 12 suspected militants and three other people.

Meanwhile, investigators concluded that two missing US Marine fighter jets likely collided over southern Iraq, a senior US defense official said yesterday at the Pentagon. US officials in Baghdad said the body of one pilot was found and that the search for the planes was continuing.

Separately, the American military said US-led forces recovered a letter that appeared to be addressed to Jordanian-born militant Abu Mussab Al-Zarqawi complaining about low morale among his followers and the incompetence of leaders in his terror network.

Jaafari had promised to form a government that would win over the Sunnis, offering them six ministries and a deputy prime minister’s slot. But members of his Shiite-dominated alliance rejected candidates with ties to Saddam’s brutal regime.

After months of wrangling following historic parliamentary elections on Jan. 30, Jaafari drew up plans for a 37-member Cabinet that so far includes 15 Shiite ministers, seven Kurds, four Sunnis and one Christian. Two of the four deputy prime ministers were also sworn in yesterday, a Shiite and a Kurd.

Jaafari blamed the delay in filling the remaining Sunni posts on divisions among themselves and predicted the matter would be resolved in two to three days.

“But we are not in a hurry,” he told reporters after the ceremony. “We want the choice to be accepted by all the Iraqi people.”

Further complicating negotiations are demands by Kurdish leaders for the Human Rights Ministry, which Jaafari had intended to offer to a Sunni, lawmakers said. There has also been competition within Jaafari’s own alliance for the Oil Ministry.

President Jalal Talabani, a Kurd, wished the new Cabinet well in its historic task “to achieve a unified democratic Iraq.”

Underscoring lingering divisions, however, many lawmakers stayed away from the ceremony, which took place in a half-empty hall inside Baghdad’s heavily fortified Green Zone. They included Ghazi Al-Yawar, a Sunni leader and one of two vice presidents who earlier complained not enough Sunnis were included in the new government.

Former Prime Minister Iyad Allawi, a secular Shiite whose caretaker government took charge of the country while Jaafari struggled to form his Cabinet, was also absent. His office said he was out of the country, but declined to specify where.

The new government will hold its first meeting within days, Jaafari said.

The Zarqawi letter was seized during a raid in Baghdad on Thursday that also yielded an undated document listing targeting information and sketch maps for kidnappings and bombings, the US military said in a statement.

The military said it was written by Abu Asim Al-Qusaymi Al-Yemeni, whom they identified as a member of Al-Qaeda in the Land Between the Two Rivers, one of the former names used by Zarqawi’s Al-Qaeda in Iraq terror group.

The letter, dated April 27, was addressed to “the sheikh,” a title used by Zarqawi’s followers to refer to their leader, the military said.

The military has claimed similar finds in the past. In February last year, the military released a letter it said was written by Zarqawi complaining that if insurgents failed to prevent the handover of sovereignty, “then there will be no choice but to pack our bags.” Postings on websites known for their militant content questioned the document’s authenticity.

Near the Syrian border on Monday, coalition forces tracked down and confronted suspected members of Al-Qaeda in Iraq, the US military said. The fighting, which included a US airstrike, killed 12 militants and injured a 6-year-old girl, the military said. Six coalition soldiers also were wounded, it said, without specifying their nationalities.