After showing the hostage's plea, the tape aired on Arab satellite Al Jazeera showed the South Korean hostage kneeling in front of three masked men, two of them armed with Kalashnikov rifles.

The man standing in the middle read a statement in Arabic, in which he gave South Korea 24 hours from sunset Sunday to meet its demand.

The statement issued a hair-raising warning, "We ask you to withdraw your forces from our land and not to send any more troops, and if not, we'll send you this Korean's head."

The statement said that the 24-hour deadline would expire at sunset on Monday Iraqi local time.

The video came two days after news of the beheading of American hostage Paul Johnson by al-Qaida-linked militants in Saudi Arabia, and an announcement Friday by South Korea that it will send 3,000 soldiers to northern Iraq beginning in early August.

Once the deployment is complete, South Korea will be the largest coalition partner in Iraq after the United States and Britain.

South Korea plans to send 900 troops to Kurdish-controlled Irbil in early August, followed by about 1,100 troops between late August and early September. An additional 1,000 soldiers will travel to Iraq later.

South Korea already has 600 military medics and engineers in the southern Iraqi city of Nasiriyah.