US national Aaron Mark DeHaven was arrested last month from a residential area in the northwestern city of Peshawar.
"The court has extended the judicial remand till March 18," public prosecutor Javed Ali told AFP.
The local magistrate's court extended his detention because documents relating to his case were in another court where DeHaven's bail application is pending, Ali said.
DeHaven's earlier bail plea was rejected last week, but the additional and sessions judge court was due to give its ruling on an appeal later on Monday.
Police say DeHaven's Pakistani visa had expired in October, and that he was working for security contractor Catalyst Services, providing security and accommodation to foreigners working on development projects in the region.