ACCRA, Ghana — The Obama administration is readying new sanctions on Syrian President Bashar Assad's regime and its allies as U.S. Secretary of State Hillary Rodham Clinton heads to Turkey for weekend talks with top Turkish officials and Syrian opposition activists.

Senior U.S. officials traveling with Clinton as she wraps up a nine-nation Africa tour in Ghana and Benin before flying to Turkey on Friday said the fresh sanctions aimed at hastening Assad's ouster were imminent. The officials spoke on condition of anonymity because they were not authorized to preview the move.

The sanctions are expected to complement existing penalties, which have targeted Assad's inner circle, including his entire Cabinet, along with Iranian individuals and entities that have been providing support to the regime.