An Iraqi terrorist group claimed on Saturday that it had killed captured U.S. Marine Cpl. Wassef Ali Hassoun (search).

The group, calling itself the Ansar al-Sunna Army (search), said in a written statement on an Islamic web site that Lebanese-born Hassoun's throat had been slit. It also said it had taken another hostage but did not give details.

Lebanon's state-run news agency reported early Sunday that Hassoun had been killed. The National News Agency (search) cited the Foreign Ministry, which was informed of the death by Lebanon's charge d'affairs in Baghdad. The agency did not say how Hassoun's death had been confirmed but quoted Foreign Minister Jean Obeid condemning the killing as "irreligious, immoral and inhumane."

If confirmed, Hassoun's slaying would be the fourth death of a foreign hostage in the region since May.

The U.S. military said it was investigating the report of the 24-year-old's death. It was not immediately possible to verify the authenticity of the group's statement.

Neighbors walked up and left flowers and notes by Hassoun's West Jordan, Utah (search), home, where his family remained in seclusion. The family received few visitors; police Capt. Gary Cox and a local imam were among those who entered their home Saturday afternoon.

"Every family has a different way of dealing with the crisis. This family prefers less attention," Imam Shuaib-Ud Din said following a brief meeting with the Hassoun family. "They don't like the media outlets to be pounding on their door. They would like some privacy."

Din, the imam at Khadeeja mosque in nearby West Valley City, also cautioned the public against automatically believing reports out of the Middle East.

"We hope it is a rumor," he said.

It seemed unlikely that the family would come out to make a statement to the media, who were still parked across the street. The family's split-level home was surrounded by 30 American flags, placed there by local Boy Scouts earlier this week.

West Jordan city leaders said they planned to ask for a moment of silence for the Hassoun family Saturday night at the town's annual Fourth of July (search) celebration.

A New Threat in Iraq

"We would like to inform you that the Marine of Lebanese origin, Hassoun, has been slaughtered. You are going to see the video with your very eyes soon," said the statement on the Arabic-language Web site. It was signed in the name of the group's leader, Abu Abdullah al-Hassan bin Mahmoud.

The group called itself the Ansar al-Sunna Army in Qaim, a town on the Iraqi border with Syria (search) that has seen frequent clashes between U.S. troops and militants. The message was dated June 20, the day the military said Hassoun was first reported missing — though the posting was dated Saturday.

"We will show a new video of the detention of a new infidel hostage and as recently promised, the beheading of rotten heads," the statement said.

"Withdraw your army and you will be safe," it said. "Or else we will keep doing what we are doing."

On June 27, the Arab television station Al-Jazeera (search) broadcast a videotape showing Hassoun blindfolded, along with a statement from militants threatening to kill him unless the United States releases all Iraqis in "occupation jails."

In that initial statement, the kidnappers identified themselves as "Islamic Response," the security wing of the "National Islamic Resistance - 1920 Revolution Brigades" referring to the uprising against the British after World War I.

Saturday's claim on Hassoun's death was issued on the same Islamic extremist Web forum where footage was posted last month showing the beheading of U.S. engineer Paul M. Johnson Jr., in Saudi Arabia. The site also often carries claims of attacks by Abu Musab al-Zarqawi, a Jordanian militant said to be operating in Iraq.

Al-Zarqawi's movement claimed responsibility for the beheading of Kim Sun-il, a South Korean who worked for a company delivering supplies to American forces, and Nicholas Berg, an American businessman, whose body was found in Baghdad in May. Johnson's slaying was claimed by Al Qaeda-linked militants in Saudi Arabia, and pictures of his severed head were posted on the Internet.

Another militant group in Iraq claimed last week that it had killed Spc. Keith M. Maupin, an American soldier who had been held captive since April. The military has not yet confirmed that Maupin was shown in grainy video footage of a man being shot in the back of the head.

In Saturday's statement, the militants said they used a woman to trap Hassoun. "As your soldier had a love affair with a young Arab woman, he has been lured from the base," the statement said.

The U.S. military said Hassoun had been absent without authorization since July 20, though after the video was shown it listed his status as "captured."

The New York Times, citing a Marine officer who spoke on the condition of anonymity, has reported on its Web site that Hassoun had been traumatized after seeing one of his sergeants killed by a mortar, and was trying to make his way back to Lebanon. The officer told the paper that Hassoun sought the help of Iraqis on the base, was betrayed by them, and was handed over the extremists.

Hassoun's eldest brother, Mohammad, who lives in a Salt Lake City suburb, denied the report.

Ansar al-Sunna Army claimed responsibility for the twin homicide attacks on the Patriotic Union of Kurdistan and the Kurdistan Democratic Party offices in Irbil on Feb. 1 that killed 109 people.

At the time, the U.S. military in Iraq believed the group was an offshoot of Ansar al-Islam, but this view later changed. There has been speculation that the group was formed from among Iraqi followers of the strict Wahhabi sect of Sunni Islam, which is widely followed in neighboring Saudi Arabia. Critics of the sect accuse it of fostering extremism.

The Associated Press contributed to this report.