An Iranian Embassy official in Syria said 48 Iranian pilgrims have been kidnapped from a bus in Damascus.
Majid Kamjou told Iranian state television that "armed terrorist groups" seized the pilgrims who were on their way to the airport on August 4.
Kamjou said he had no information about their fate, but maintained Syrian authorities had begun a search.
Syrian state media reported that the Iranians had been planning to visit the Sayyeda Zeinab mosque, a popular pilgrimage site for Shi'ite Muslims.
The incident is the latest in a string of kidnappings since the uprising began against Syrian President Bashar al-Assad, who is supported by Tehran.
In December, five Iranian engineers were kidnapped in Homs, while a group of pilgrims were kidnapped in January and February.
Iranian media say most of them have been released.
Based on reporting by AFP, Reuters, and dpa