A senior commander in Iran's Revolutionary Guard has confirmed it is training volunteer "advisers" to serve alongside President Bashar Assad's forces in Syria.

General Mohsen Kazemeini says Iran feels an "obligation" to send "military advisers" to Syria to protect Shiite shrines at the request of the Assad government. His comments were posted on an official Guard website Wednesday.

Tehran acknowledges that Guard officers are on the ground in Syria in an advisory role, but denies it has sent combat troops. A number of Iranian soldiers have been killed in Syria, including high-ranking officers.

Wednesday's statement was the first time Iran acknowledged training volunteer advisers.

Iran is a key ally of Assad and has provided military and financial support throughout the five-year civil war.