BAGHDAD, Iraq — Hundreds of Iraqi soldiers and police commandos, supported by U.S. military helicopters, maintained positions yesterday around the central Iraqi town of Madain, where residents disputed widespread reports that scores of Shiite Muslims were held hostage by Sunni extremists.

In a search of homes on the outskirts of the town, Iraqi police found only three hostages, one of them Kurdish, said Police Capt. Ahmad Kamal. "And they were kidnapped because they were working for Americans, not for the reason they were talking about," he added.

Officials in the Iraqi capital, meanwhile, moved quickly to lessen inflamed sectarian sentiments sparked by allegations a day earlier of a hostage situation in the agricultural town about 18 miles southeast of Baghdad. The alleged hostage-takers reportedly were demanding that Shiite residents move out of town.

Legislators set up a committee to look into the matter. Shiite religious and political figures who had related detailed accounts of mass kidnappings Saturday continued to express concern but did not repeat those accounts. Interim Prime Minister Ayad Allawi appealed for calm.

"These wild acts of destroying peaceful houses, kidnapping of innocent people and assaulting properties and families will not go without punishment," he said. "I call for all political and religious entities to ask for calming down and to stop any nervous actions that lead to dangerous consequences."

The political vacuum in Baghdad has made dealing with the troubles in Madain more difficult. Allawi is running a caretaker government while Iraq's newly nominated prime minister, Ibrahim al-Jaafari, forms his Cabinet. He is not expected to complete that task for at least another week, an al-Jaafari aide said yesterday.

Qassim Dawoud, interim minister of state for national security, told the newly elected National Assembly that five battalions of Iraqi army and police surrounded Madain and that the government is "not sure" about the number of hostages.

"We are also following the situation very closely," he said, adding that "by the end of this week we are going to launch a large-scale operation in the area to uproot terrorists from there."

Dawoud added, "We have to acknowledge the truth that there is an attempt to draw the country into a sectarian war."

The situation in Madain, a religiously mixed town of Sunni and Shiite families, remained murky yesterday. A Washington Post correspondent saw no indications of a hostage situation, though Iraqi police and soldiers searched cars going in and out of the town.

"We don't have any missing person kidnapped by armed men," said Saeed Abdul Mohsen Maksusi, prayer leader of a Shiite mosque.

The correspondent said many of the town's shops were shuttered and residents at home because they expected the Iraqi forces to move into the town. Seven U.S. Apache helicopters flew low over the town.

The U.S. military press office in Baghdad, however, denied U.S. forces were involved.

A paper on the door of the main mosque in Madain carried a message from the insurgent group led by Abu Musab al-Zarqawi, the correspondent said. It charged that the "enemies of God" had fabricated reports about a hostage crisis to justify a military attack targeting Sunnis in Madain.

Meanwhile, the Iraqi government announced the capture over a month ago of a prominent insurgent leader who also is the nephew of Izzat Ibrahim Douri, one of former Iraqi leader Saddam Hussein's closest advisers. Hashim Hussein Radhan Jabouri was captured March 7 in Salah Al-Din province north of Baghdad, the government said in a statement.

Jabouri, an officer in the former Iraqi Intelligence Service, allegedly got money from Douri to set up insurgent activities in Iraq, it added. There is a $10 million reward for information leading to Douri's capture.

Also, a U.S. aid worker who helped civilians caught in the crossfire of war was killed by a suicide car bomber on the dangerous road to the airport, the U.S. Embassy in Baghdad said yesterday.

U.S. aid worker Marla Ruzicka was killed.

Marla Ruzicka, 28, was on her way to the airport Saturday afternoon when the bomber targeted a U.S. convoy, said Adam Hobson, an embassy spokesman. Four people died and five were wounded, in the explosion, Hobson said.

The organization Ruzicka founded three years ago, Campaign for Innocent Victims in Conflict, provided assistance to the families of people killed or injured during U.S. military campaigns in Iraq and Afghanistan.

Information from The Associated Press is included in this report.