U.S. aircraft Wednesday mounted four strikes in Fallujah on what the U.S. military said were safehouses used by Abu Musab al-Zarqawi's (search) terror network.

A Sunni Muslim clerical group demanded that the Iraqi government prevent any full-scale U.S. attack on Fallujah (search), hoping to muster the same public anger that forced the Marines to abandon a siege of the city last spring.

Meanwhile, Iraq's interim government complained Wednesday that the United Nations (search) isn't doing enough to help prepare for January elections, saying the organization has sent fewer electoral workers than it did when tiny East Timor voted to secede from Indonesia.

In other violence, 11 American soldiers and an Iraqi interpreter were wounded when two car bombs exploded in Samarra, a city that U.S. and Iraqi forces have hailed as a success story since taking it from insurgents last month. An Iraqi child was killed and a civilian was wounded, the Army said.

A suicide bomber in Baghdad detonated his car near a U.S. patrol on the airport road, wounding two American soldiers and two Iraqi policemen. The road is among the most dangerous in the capital. Zarqawi's terror organization claimed responsibility for the attack, though it was not immediately possible to verify that the Internet posting was authentic.

The U.S. State Department said it had "credible information that terrorists are targeting civil aviation."

"Civilian and military aircraft arriving in and departing from Baghdad International Airport have been subjected to small arms and missiles," the State Department said Wednesday in a statement. "Civilian aircraft do not generally possess systems, such as those found on military aircraft, capable of defeating man-portable, surface-to-air missiles."

U.S. and Iraqi forces have stepped up operations seeking to curb insurgent violence so that Iraqi voters throughout the country can choose a new transitional government in January. The elected assembly is to draft a new constitution in a major step toward democratic rule after decades of tyranny and military occupation.

But Foreign Minister Hoshyar Zebari (search) complained that the United Nations has not sent enough election experts to help prepare for the balloting.

"It is unfortunate that the contribution and participation of U.N. employees in this process is not up to expectations," Zebari told reporters.

He said the number of U.N. workers expected to help in the election was far smaller than the 300 workers the United Nations sent for the 1999 independence referendum in East Timor.

"Judging by the size of the process in Iraq and its complexity, we definitely need a larger U.N. presence in Iraq, at least to bestow trust upon the electoral process," Zebari said.

The United Nations pulled its international staff out a year ago after bombings at its Baghdad headquarters killed 22 people, including the top U.N. envoy, Sergio Vieira de Mello.

U.N. chief Kofi Annan has since allowed a team to return to help with elections but imposed a ceiling of 35 non-Iraqi staffers. In the meantime, the United Nations is training Iraqis outside the country so they can come back and instruct other Iraqis on how to run an election.

Annan said Tuesday in London that he had sought to form a U.N. brigade to guard U.N. workers and facilities so more staffers could be sent in, but complained he had gotten no offers of troops.

U.N. officials in New York said Wednesday that Fiji was the only nation to respond to Annan's request and would send 130 soldiers to Iraq next month to protect senior staff and U.N. offices. Spokeswoman Marie Okabe said U.N. officials also were talking with the U.S.-led coalition about providing troops to protect the perimeter of U.N. facilities and U.N. staffers working outside the U.N. offices in Baghdad.

"The secretary-general has been doing his best to try to get as much support to the Iraqi Electoral Commission and the process, and ... as circumstances permit we would want to increase the assistance to the best of our ability," Okabe said.

Since the bombings at the U.N. headquarters a year ago, attacks on foreigners have only grown worse. CARE International suspended operations in Iraq on Wednesday, a day after the aid group's director for Iraq, Margaret Hassan, was abducted. Her family said Wednesday they had received no demands from the kidnappers.

U.S. officials blame much of the violence on al-Zarqawi's Tawhid and Jihad movement, which is believed headquartered in the insurgent bastion of Fallujah, 40 miles west of Baghdad.

The U.S. command said its warplanes struck more targets Wednesday believed connected to al-Zarqawi's fighters.

"Intelligence reveals that anti-Iraqi forces have planned to use the holy month of Ramadan for attacks against the Iraqi interim government and innocent Iraqis," the command said.

It denied witness reports that U.S. aircraft attacked a women teacher's college and a house where a family of six was killed. The command accused "a known Zarqawi propagandist" of "passing false reports to the media."

The Iraqi government had been negotiating with Fallujah representatives in hopes of ending the standoff in the city and allowing the Iraqi National Guard to take over security duties there. But the talks broke down last week over what the Fallujah negotiators called the "impossible condition" that the city hand over al-Zarqawi and other foreign fighters. Fallujah leaders claim al-Zarqawi isn't there.

On Wednesday, the Association of Muslim Scholars, a Sunni organization with links to some insurgents, demanded that the government persuade the Americans to refrain from a a full-scale attack on Fallujah.

"Iraqis consider Fallujah the symbol of their steadfastness and pride," said Sheik Harith al-Dhari, head of the association. "There is no reason to attack Fallujah. Attacking Fallujah is the wish of the occupation troops and some interim government officials."

Public outrage forced the Americans to halt a three-week siege of Fallujah in April, a move that led to the takeover of the city by extremist clerics and their armed followers.

In other developments Wednesday:

— Staff Sgt. Ivan L. "Chip" Frederick, 38, pleaded guilty to five charges stemming from the Abu Ghraib prison scandal. Frederick, the highest-ranking soldier charged in the abuse case, was expected to be sentenced Thursday.

— The U.S. command reported that a 26-year-old male security internee died Tuesday at the U.S.-run Camp Bucca prison near Umm Qasr in southern Iraq. It said an investigation was under way to determine the cause of death.

— Two Egyptian mobile telephone engineers were released by kidnappers who abducted them from their Baghdad office last month, their employer said. The company said the release was mediated by al-Zarqawi's organization.