Other Shiite militias in Iraq have acknowledged sending members to Syria, but it is the first time that the Iraqi Hezbollah has hinted that its members are fighting there.
The fighter, Afrad Mohsen al-Hemedawi, was killed while defending a Shiite holy shrine in Syria, according to the official of the Hezbollah Brigades, who requested anonymity because he was not authorized to publicly discuss the issue. The official said the man was killed on March 30 and buried on April 1.
An official statement from the group also confirmed his death.
A video posted on YouTube showed thousands of men and Shiite clerics, clad in robes and turbans, marching at al-Hemedawi's funeral. Men carried his coffin, which was covered with red flowers and wrapped in the yellow-and-green flag emblazoned with an assault rifle that is the symbol of the Hezbollah Brigades. Young men in black uniforms and caps bearing the Hezbollah Brigades flag walked alongside. Another two men carried a large portrait of the slain fighter.
The Hezbollah Brigades official said the public funeral for al-Hemedawi was designed to send a message to their Sunni militant rivals fighting in Syria that they will not abandon their holy sites.
Iraq and Syria's other neighbors—Jordan, Lebanon, Turkey and Israel—all fear the spillover effects of the two-year civil war, which has killed 70,000.
Iraq, Lebanon and Syria all have populations with a mix of rival sects and officials fear the conflict could cause sectarian warfare between Sunnis and Shiites to spread throughout the region.
Iran and many Iraqi Shiite militants support Syrian President Bashar Assad, while many Iraqi Sunnis back the largely Sunni rebels trying to oust him. Most of the hard-line Sunni extremists fighting with the Syrian rebels appear to have coalesced around the Nusra Front, which is an offshoot of al-Qaida militants in Iraq.
The Hezbollah Brigades is not connected to the better-known Lebanese Hezbollah, but both are backed by Iran and have been designated as terrorist groups by the U.S. State Department.
The official said al-Hemedawi and other fighters were sent to Syria particularly to protect Shiite holy sites, including the prominent shrine in Damascus for the Prophet Muhammad's granddaughter, Zainab. The official said they feared the shrines would be attacked by Sunni jihadists if they were left undefended. Sunni extremists see the presence of shrines as heretical, and also have attacked those visited by Sunni Muslims.
He said their fears stem from the 2006 bombing of the Shiite al-Askari shrine in the Iraqi city of Samarra. That attack was blamed on al-Qaida in Iraq and set off years of retaliatory bloodshed between Sunni and Shiite extremists that left thousands of Iraqis dead and pushed the country to the brink of civil war.