Police arrested a man from Mongla Port residential area of Khulna district on Thursday night allegedly for making derogatory remarks about Prophet Muhammad (pbuh) on social networking site Facebook.   The arrestee is Anjon Das, a resident of the area.   Sabbirul Alam, officer-in-charge of Khalishpur Police Station, said Anjon Das made derogatory comments about Prophet Muhammad (pbuh) on his facebook page and the comment went viral, creating a tense situation in the area.   On information, police went to his residence and arrested him.   A case was filed under the Digital Security Act.