BAGHDAD - Gunmen killed an Oil Ministry official on Thursday and escalating violence claimed at least 18 more lives, fuelling fears Iraq may be moving towards civil war.
The oil official, Ali Hameed, was shot outside his home as he left for work, a police official said.
Mainly Sunni Muslim insurgents have stepped up attacks on officials and security forces since a Shi'ite-led government was announced last month. They have killed more than 500 people in a campaign that has challenged government promises of stability.
In the worst violence on Thursday, seven people were killed in clashes in the northern city of Mosul after insurgents attacked the house of a local Sunni Muslim politician, witnesses and hospital officials said.
The politician, Fawwaz al-Jarba, said his driver and three guards were among the dead. He said U.S. troops backed by helicopters responded to his request for help.
In Baghdad, a university professor was shot dead, an Iraqi soldier was killed in a suicide bombing, and four other Iraqi soldiers were kidnapped. A roadside bomb also killed an American soldier in the capital, the U.S. military said.
The escalation in violence has raised concerns the country could erupt into a full-scale civil war. Discoveries of people killed execution-style and dumped at various sites -- 50 have been found since Saturday -- have stirred sectarian passions.
Most victims were Shi'ite Muslims but some were Sunnis.
Four more bodies were found on Thursday, this time just south of Saddam Hussein's home town of Tikrit. Police said they had been shot dead.
SECTARIAN TENSIONS
A funeral service was held for Muhammad al-Allaq, a Shi'ite cleric who was gunned down on Wednesday, relatives said.
Top Sunni cleric Harith al-Dhari has publicly accused the Badr Brigades, the militia of the main Shi'ite political party, of assassinating Sunni preachers.
It was the first time Dhari publicly accused the armed wing of the Supreme Council of the Islamic Revolution in Iraq (SCIRI), which was part of the Shi'ite coalition that won a majority in parliament in the historic Jan. 30 elections.
Dhari's Muslim Clerics Association called for a three-day closure of Sunni mosques in protest at the killings and warned that Sunnis would not keep silent.
The top Badr Brigades official denied the accusations and said Sunnis and Shi'ites should avoid sectarian strife.
Shi'ite Arabs and Kurds, who dominate Iraq's parliament, have promised to give Sunni Arabs a key role in politics and in drafting a new constitution, even though the Sunni Arab minority won only 17 of parliament's 275 seats.
Sunni Arabs were the most powerful group in Iraq during Saddam Hussein's rule, but largely stayed away from the January elections and make up the backbone of the insurgency.
So far, most Shi'ites have heeded calls by moderate clerics to show restraint in the face of suicide bombings and insurgent attacks that have killed thousands. But the recent explosion of violence has raised questions over their patience.
In Mosul, hospital officials said two people were killed when a bomb exploded prematurely in the car they were driving on a suicide mission. In the northern town of Baiji, four soldiers from the Iraqi army were kidnapped at dawn.
Police said a roadside bomb killed two policemen in Baquba, and a police officer and his father were shot dead travelling in their car in Samarra.
Many of the deadliest attacks have been blamed on Al Qaeda's leader in Iraq, Abu Musab al-Zarqawi, who called for suicide attacks against U.S. forces to be stepped up in an audiotape message attributed to him on Wednesday.
He also defended the killing of "innocent Muslims" in suicide bombings, saying it was legitimate in a holy war.
Zarqawi's followers issued a new warning against Iraqi forces on Thursday in leaflets in Baiji, residents said.
"Leave your jobs within four hours otherwise you will get yourself killed," said the leaflets hung on mosques.