University students have staged sit-down strikes in support of the anti-government protests in Iran, despite an intensifying crackdown by authorities.
Videos and photographs posted online showed young men and women gathered in corridors, courtyards and roads at campuses in Tehran and other cities.
Some held placards warning there would be no classes until fellow students arrested while protesting were freed.
Activists say 300 have been detained since the unrest erupted six weeks ago.
The protests were sparked by the death in custody of a young woman who was accused by morality police of wearing her hijab “improperly”.