CAIRO, Egypt (AP) _ An Iraqi militant group has beheaded its South Korean hostage, Al-Jazeera television reported Tuesday.

The pan-Arab station said it had received a videotape showing that Kim Sun-il had been executed.

Kim, 33, worked for a South Korean company supplying the U.S. military in Iraq and was abducted last week, according to the South Korean government.

Al-Jazeera, which had not broadcast the tape, said the execution was carried out by the al-Qaida-linked group Monotheism and Jihad.

News of the apparent beheading reached the White House in the midst of a briefing by spokesman Scott McClellan, who said he was not aware of the report.

``That would be horrible news,'' McCelllan said. ``There simply is no justification for those kinds of atrocities that the terrorists carry out. We've seen some of the barbaric nature of the terrorists recently when it comes to an American citizen that was killed in Saudi Arabia and it is a reminder of the true nature of the terrorist.''

Kim's kidnappers had initially threatened to kill him at sundown Monday unless South Korea canceled a troop deployment to Iraq. The Seoul government rejected the demand, standing firm with plans to dispatch 3,000 soldiers starting in August.

NKTS, a South Korean security firm doing business in Iraq, told the AP in Baghdad earlier Tuesday that Kim was still alive and that negotiations for his release continued, with the company president expected to arrive in Baghdad from Seoul by Wednesday.