DUBAI, United Arab Emirates - A Web site linked to an Iraqi militant group showed a video of what was purported to be the killing of 12 Nepalese workers by militants who had kidnapped them.

The Nepalese Foreign Ministry said it could not confirm the report of the hostages' deaths. The 12 had been reported kidnapped Aug. 20.

The video showed a masked man in desert camouflage apparently slitting the throat of a blindfolded man lying on the ground. The blindfolded man moans and a shrill wheeze is heard, then the masked man displays the head to the camera before resting it on the decapitated body.

Other footage showed a man firing single shots from an assault rifle at the back of the heads of 11 others. Blood seeps from their bodies on to the sand. Still photos of similar scenes were posted on other Web sites known for militant Islamic comment.

A statement on the Web site signed "Ansar al-Sunna Army" vowed to keep fighting the Americans in Iraq.

"America today has used all its force, as well as the help of others, to fight Islam under the so-called war on terror, which is nothing but a vicious crusade against Muslims," the statement said.

At the end of the four-minute video, a man reads another statement off-camera, vowing to fight the Iraqi government.

"We will work on exterminating them until the last fighter," he said.

Iyad Mansoor, director-general of the Morning Star Company, a Jordan-based services firm which had contracted the 12 Nepalese workers for jobs in Iraq, said he had no information on the Nepalese captives.

"I'm shocked to hear such news," he told The Associated Press. "The last I heard was that the Nepalese government was in contact with Iraqi clergymen and others in an effort to set the 12 men free."

In an Aug. 20 Web statement, the little known Ansar al-Sunna Army claimed to be holding 12 Nepalese hostages and demanded Nepal stop sending workers to Iraq. The same group later claimed to have kidnapped and beheaded an Arab-American it said was a CIA spy, but the U.S. Embassy in Baghdad had said it was unaware of an American hostage.

On Sunday, a tape on the same Web site showed the 12 Nepalese, one of them draped in an American flag reading a statement.

The speaker said each of the 12 men were offered $2,500 a month to work in Iraq.

"The Americans assured us that the situation in Iraq is stable and not dangerous," he said. "America lied to us. ... The situation here is not under American control."

He warned others against coming to Iraq.