In the UN Security Council, ambassadors attending a debate on postconflict situations issued a series of denunciations of the hostage killing.
South Korea's ambassador, Kim Sam-hoon, vowed his country would maintain forces to help secure Iraq.
"The Republic of Korea believes strongly in the efforts of the international community to rebuild a free and democratic Iraq and the Republic of Korea remains committed to this noble goal," Sam-hoon said.
In Seoul, South Korean officials said they would keep their 600 troops -- mostly military medics and engineers -- in Iraq and confirmed plans to send about 3,000 more by August. But the government ordered its nonessential civilians to leave Iraq.
The victim of yesterday's beheading, Kim Sun-il, worked for a South Korean company supplying the U.S. military in Iraq.
UN Secretary-General Kofi Annan released a statement calling the murder of Kim a "heartless crime which no political or other cause can justify."
The foreign minister of the Philippines, Delia Domingo Albert, whose country currently holds the Security Council presidency, also made a statement in the chamber. On behalf of the council, she urged the international community to stand united against the scourge of terrorism.
Thousands of citizens from the Philippines work as cooks and maintenance workers at U.S. military installations across Iraq.
In comments earlier to reporters, Albert said her government has advised Filipinos in Iraq to avoid conflict zones, but added it was difficult to identify such areas.
"We have actually about 4,000 or 5,000 workers in the area and many of them have been deployed from neighboring countries and we have advised everyone. We have a team that's working very closely to look into the security of our people in the area," Albert said.
In Washington yesterday, Hungarian Prime Minister Peter Medgyessy said Hungary had not changed its commitment to keeping troops in Iraq to stabilize the country.
Medgyessy spoke after meeting with U.S. President George W. Bush. Hungary has contributed about 300 troops to the international coalition in Iraq and last week suffered its first military fatality.
Medgyessy told reporters he thought there was openness within Europe to an agreement among NATO members to help train Iraqi security forces. NATO leaders hold a summit next week in Istanbul.