The Pakistani national was detained by counter terrorism officers on Monday evening after arriving on a flight from Dubai.
Detectives say the man was arrested on suspicion of being in possession of a document likely to be of use to a person committing or preparing an act of terrorism.
The document in question was found in the man's possession.
The man is still being questioned by police.
He was entering the UK on a student visa, and studying at a fully accredited institution, although the police refused to name it.