Two South Korean aid workers were set free Tuesday, a day after being detained by a Shiite (search) group in southern Iraq, a South Korean Foreign Ministry official said.

The two men were doing relief work in the southern city of Nasiriyah (search) on Monday when shooting erupted between Italian forces and Shiite militiamen, said the official.

"During this gunfight, the Shiite men held the South Koreans because they were foreigners," the official said on condition of anonymity. "But after finding that they were South Koreans, the Shiite men released them the following day."

The two were in Baghdad following their release, the official said. Seoul has received no report of injuries of the men.

South Korea's Yonhap news agency and Japan's Kyodo news agency had cited French radio reports as saying the two men were kidnapped in southern Iraq by a Shiite militia group called the al-Mahdi Army (search).

Kyodo said they were taken while the militia battled Italian troops near Nasiriyah.

The al-Mahdi Army demanded the pullout of Italian forces in exchange for their release, French radio reported, according to Kyodo.

The al-Mahdi Army is a private militia loyal to Shiite cleric Muqtada al-Sadr (search). The militiamen have battled troops from the U.S.-led coalition for three days.

South Korea has been on guard against possible attacks and reprisals for its contributions to the U.S.-led alliance. Seoul plans to send 3,600 troops to Iraq, making it the biggest coalition partner after the United States and Britain.