A Syrian rebel group which has claimed responsibility for the kidnapping of 47 Iranians pilgrims in Damascus said Monday that three of the hostages were killed in a shelling by government troops on areas at the outskirts of the capital Damascus.

Al-Baraa Brigade of the Free Syrian Army announced on its Facebook page that "three of the Iranian prisoners were killed in fierce shelling on a Damascus suburb."

The group has threatened to "execute the prisoners who are proven members of the Revolutionary Guard if the shelling continues." Tehran, a main ally of the Syrian regime, has denied that any of the kidnapped pilgrims are members of the Revolutionary Guard.

The Iranian pilgrims were detained Saturday by the Syrian rebels.