A 31-year-old student from Denmark was arrested by Iranian police in Tehran for attending a recent protest, a Danish journalists group said Friday.

The Danish Union of Journalists said University of Southern Denmark student Niels Krogsgard, who disappeared Thursday, was arrested in the Iranian capital after police officers clashed with anti-government protesters, The Copenhagen (Denmark) Post reported.

The union said it obtained its information about Krogsgard from the International Federation of Journalists in Brussels.

Krogsgard, who was in Iran as part of a university project on Iranian politics, was with a fellow student at Thursday's protest when the pair became separated after police forces fired tear gas.

Charlotte Slente, spokeswoman for the Danish Foreign Ministry's citizens' service agency, told the Post the ministry could not confirm Krogsgard's arrest.

"We're using all our efforts on localizing Niels Krogsgard," Slente said. "The embassy is in contact with the Iranian authorities to help track him down."