Denmark's journalists union says one of its members is being held in a jail in Tehran.

The Danish Union of Journalists says Niels Krogsgaard "apparently was arrested in connection with a demonstration on Wednesday."

The union said Friday that Krogsgaard is a Danish journalism student who went to Iran to work on an academic paper on Iranian politics. It didn't give his age.

The union said it located Krogsgaard in an Iranian jail with the help of the Brussels-based International Federation of Journalists.

A reporter for French news agency Agence France Presse was detained Wednesday while covering a state-sanctioned rally to mark the 30th anniversary of the U.S. Embassy takeover. Anti-government protesters also clashed with police in counter-marches.