Azerbaijani security officials have raided the Baku office of the nongovernmental organization IREX.
Security officials confiscated computers and documents from IREX, RFE/RL reports.
IREX employees said the officials provided a legal warrant to search the premises but gave no reason for the raid.
IREX's bank assets in Azerbaijan were frozen on July 31.
IREX, which was founded in 1968, is an international nonprofit organization that promotes democratic reforms in some 125 countries worldwide.
The raid is the latest in a string of attacks by Azerbaijan on civil society institutions.
The Baku bank accounts of Transparency International and the National Democratic Institute (NDI) were also frozen.
The NDI closed its office in Azerbaijan.
Ramiz Mehdiyev, the head of Azerbaijan's presidential apparatus and President Ilham Aliyev's chief domestic policy adviser, said on August 29 that independent media are "anti-Azerbaijani forces" financed from abroad.