In remarks to commanders of the elite Revolutionary Guard today, Ayatollah Ali Khamenei says authorities should take concerns about "infiltration" seriously and that political factions should not use the issue against each other.
His comments appeared to lend support to a recent wave of arrests of pro-Western writers and journalists, which hard-liners in the judiciary and security services have said is necessary to prevent Western infiltration.
Iran's moderate President Hassan Rouhani has criticised the arrests.