At the start of the trial on Monday, the judge rejected defense appeals, according to Elmar Suleymanov, the lawyer for one of the suspects. Suleymanov claimed the investigators have failed to provide sufficient proof to back up the case.

The six men are part of a group of 26 Azerbaijani citizens arrested in September on charges of joining IS.

In Monday's statement, Azerbaijani National Security Minister Eldar Makhmudov accused unidentified countries of trying to encourage radical groups in Azerbaijan.

Azerbaijan, a mostly Muslim energy-rich Caspian Sea nation, has maintained close ties with Washington and contributed troops to the U.S.-led missions in Afghanistan and Iraq.