Iranian human rights and opposition websites say more than 1,000 students have taken part in several anti-government protests this week.
The Kaleme opposition site says Iranian authorities arrested about 15 student demonstrators at Tehran's Polytechnic University Tuesday. It says five of the students remain in custody.
The demonstrators were taking part in ceremonies marking "Student Day," an annual event commemorating the deaths of three Iranian students who were killed by security forces during an anti-American protest in 1953.
Last year, demonstrators turned official Student Day gatherings into rallies against the disputed re-election of President Mahmoud Ahmadinejad. Authorities arrested several opposition activists.
On Wednesday, a Tehran prosecutor confirmed the arrests of four journalists from the leading reformist newspaper, Sharq. The arrests took place Tuesday, the same day the newspaper published an article about Iran's student movement that included interviews with government critics.
Some information for this report was provided by AP.