Tunisia's government says it has arrested one of its nationals believed to be linked to the September-11 attack on the U.S. consulate in Libya.

Interior Ministry spokesman Tarrouch Khaled said Wednesday that 28-year-old Ali Harzi was in custody in Tunis. He gave no other details.

Ambassador Christopher Stevens and three other Americans died in the attack on the U.S. diplomatic post in Libya's Mediterranean city of Benghazi.

The U.S. the State Department had no immediate comment.