Militiamen disguised as police officers kidnapped an Austrian and four US security men guarding a 49-vehicle convoy in southern Iraq in the second abduction in three days that raised suspicions of security force collusion.
Police are still searching for dozens of people still missing after a daylight raid on a Sunni-led ministry building in Baghdad on Tuesday by scores of gunmen wearing police uniforms.
In the latest kidnapping, the five Westerners were seized when the convoy of 43 trucks and six security vehicles they were guarding stopped at "what appeared to be a police checkpoint near Safwan" close to the Kuwait border on Thursday, a senior US official told AFP.
"Nineteen trucks and one security vehicle were taken by those posing as police."
The official said the kidnappers seized a total of 14 people but the Kuwait-based firm which employed the five guards said nine truck drivers were later released.
"Those not taken were not injured and reported no abductees were injured either," the US official said.
A spokesman for Kuwait-based Crescent Security said the five guards remained "unaccounted for," and added the company was in contact with the US military over the case.
The US military said that the matter was being looked into by the embassy as "those gone missing are not multinational force members."
Crescent Security "conducts convoy escort duties for an ever growing number of coalition militaries, embassies, government contractors" and others operating in Iraq, according to the company website.
The firm is a member of the "private security company association of Iraq," which groups 48 companies that provide a wide range of security services to convoys and personnel in all parts of Iraq, the website adds.
Security forces were still hunting for higher education ministry staff and visitors unaccounted for after Tuesday's daylight raid on a ministry research institute in Baghdad.
Higher Education Minister Abed Dhiab al-Ujaili said on Thursday that some 75 hostages still remained captive, including 40 of his ministry's staff.
Citing freed hostages, Ujaili said that some of the captives had been killed and many tortured.
Ujaili has stepped down from the government until it secures the release of all hostages and takes action against Shia militias suspected of carrying out the mass abduction of an estimated 150 people.
On Wednesday, government spokesman Ali al-Dabbagh played down the kidnapping, insisting that only 39 people had been seized, of whom just two were still being held.
The abduction carried out by armed men dressed in commando-style uniforms marked a new blow for Iraq's national unity government as the United States piles on pressure for more effective action against the Shia militias.
A leading Shia cleric told worshippers in a prayer sermon Friday that it would be wrong to impute a sectarian motive to all of the kidnappings rocking Iraq.
"It is not correct to call these acts as sectarianism and thus ignite sedition and send the country into a civil war," said Sheikh Abdel Mahdi al-Karbalaie, representative of Shia spiritual leader Grand Ayatollah Ali al-Sistani in the shrine town of Karbala.
"Those carrying out such cowardly acts are enemies of everyone, Sunni and Shia alike."
But a warrant issued against the leader of the main Sunni clerics' organisation while he was out of the country threatened to further fan tensions between the Shia majority and the Sunni Arab former elite.
Harith Sulaiman al-Dhari, head of the Muslim Scholars' Association, "violated the anti-terror law and the warrant is to bring him back from wherever he is," interior ministry spokesman Major General Abdel Karim Khalaf told AFP.
The government spokesman later clarified that the warrant was not for Dhari's arrest but to open a criminal investigation into his activities.
"There are investigations and an investigation warrant related to the activities of Sheikh Dhari and they are not final," Dabbagh said.
President Jalal Talabani, a Kurd, accused Dhari on Wednesday of "incitement to sectarian violence" and expressed regret that certain Arab states -- which he did not name -- were supplying the cleric with aid.
Dhari dismissed the warrant as "illegal."
Speaking to reporters in neighbouring Jordan, he accused the Iraqi government of "provoking a crisis" to cover up its own failings and vowed to return to Iraq "at the appropriate time."
Dhari's association called for calm but urged Sunni politicians "to pull out of parliament and the government," in a fresh threat to the hard-won Sunni Arab representation in the national unity administration.
The US military meanwhile announced the death of another soldier, taking its losses since the 2003 invasion to 2,859, according to an AFP count based on Pentagon figures.