A statement signed by an Iraqi insurgent group said Thursday in an Internet posting that it killed a kidnapped U.S. security consultant. The White House said it could not confirm the death.

The statement, posted on an Islamic militant Web forum, did not identify the hostage and provided no pictures, video or other evidence he had been killed. It said pictures of the slaying would be released later. The U.S. Embassy said it had no information to confirm the claim.

White House press secretary Scott McClellan said he could not confirm the death and said he had no additional information on the matter. "Any time there is an American that is taken hostage it is a priority for the administration, and their safe return is a priority for the administration," he said.

It was the first time in more than a year that a group from the Sunni-led insurgency announced the slaying of an American hostage. Another American was killed in August, and police blamed Shiite militants.

The Islamic Army in Iraq said it had killed "the American security consultant for the Housing Ministry," after the United States failed to respond to its demand of the release of Iraqi prisoners.

A video issued by the group was broadcast Tuesday on Al-Jazeera showing the hostage — identified as Ronald Schulz, 40, an industrial electrician from Alaska — sitting with his hands tied behind his back.

The group Thursday blamed President Bush for failing to respond to its demands.

"The war criminal Bush continues his arrogance, giving no value to people's lives unless they serve his criminal, aggressive ways. Since his reply [to the demands] was irresponsible, he bears the consequences of his stance," the statement said.

"Therefore the American security consultant for the Housing Ministry was killed after the end of the deadline set to respond to the Islamic Army's demands," it said.

On Tuesday, Bush said the United States will work for the return of captive Americans in Iraq but would not submit to terrorist tactics. "We, of course, don't pay ransom for any hostages," Bush said.

"What we will do, of course, is use our intelligence-gathering to see if we can't help locate them," Bush said.

Another insurgent group, the Swords of Righteousness, has set a Saturday deadline, threatening to kill four Christian humanitarian workers abducted two weeks ago, including an American, two Canadians and a Briton. A French aid worker and a German citizen are also currently being held by kidnappers.

Schulz graduated from Jamestown, North Dakota, High School in 1983, then joined the Marines. His brother, Ed, said he served in the Marine Corps from 1984 to 1991 and after his discharge, moved to the Anchorage, Alaska, suburb of Eagle River.

No one answered the phone at Ed Schulz's home Thursday.

The Rev. Doug Opp, pastor of St. John's Lutheran Church in Jamestown, where Ronald Schulz and his family were members, said before hearing Thursday's news that a prayer vigil was planned for Friday in the church sanctuary. Plans will continue for that until the news from Iraq is confirmed, Opp said.

"We're proceeding (with the vigil) until we know," Opp said.

Iraq has seen a sudden surge of kidnappings of Westerners in the past month after a relative lull. The last time insurgents announced the killing of American hostages was Sept. 21, 2004, when al-Qaida in Iraq said it had killed Jack Hensley, a civil engineer from Marietta, Ga., and Eugene "Jack" Armstrong, formerly of Hillsdale, Mich. They had been abducted days before along with a British engineer Kenneth Bigley, who was also killed.

On Aug. 2, 2005, New York freelance journalist Steven Vincent and his female Iraqi translator were abducted at gunpoint. His body was discovered that night south of Basra. The translator was seriously wounded and remains hospitalized.

Vincent was killed shortly after he wrote a column published in The New York Times claiming Basra police were of being infiltrated by Shiite militiamen. A senior British official said Islamic militants — and not Iraqi police — probably killed him.