Four foreigners have been arrested in the eastern Libyan city of Benghazi on suspicion of being Christian missionaries and printing books about Christianity, a security official said on Saturday."They were arrested on Tuesday at a publishing house where they were printing thousands of books that called for conversion to Christianity," security official Hussein Bin Hmeid said."Proselytizing is forbidden in Libya. We are a 100 percent Muslim country and this kind of action affects our national security."