Police have detained 230 boys and girls at separate parties in the Iranian capital Tehran in which alcohol was involved, according to reports.
Officers arrested 140 of the young partygoers in a garden on the outskirts of Tehran and 90 in the city centre on Thursday night.
Drinking alcohol and mixed parties of unrelated men and women are illegal and considered a sin under Islamic law in Iran.
The report said some participants posted an invitation to others to join on Instagram, and police subsequently arrested them.
The ISNA news agency said some alcoholic drinks and psychotropic drugs were confiscated.