Iran's morality police have made several raids in Tehran, in an apparent crackdown on women who flout the strict Islamic dress code.
Witnesses said dozens of young women were held in the raids on shopping centres and shops in the capital.
Police also confiscated several items of clothing deemed to be too revealing.
After winning parliamentary elections in February, hardliners warned they would not tolerate what they described as social corruption.
However, the clampdown could be the usual summer anti-vice operation, correspondents say.
Since the 1979 Islamic revolution, Iran's laws say all young women must wear the veil and a long coat that conceals their figures, or face fines or even imprisonment.
'Rebellious population'
Witnesses said scores of police - including female officers in chadors - raided the Milad commercial centres in western Tehran and took away dozens of young women in special minibuses.
Shops selling fashion clothing for women - especially bright figure-hugging coats - were also targeted.
The police chief in Tehran recently warned that anybody caught involved in what he called social corruption would be punished, the BBC's regional analyst Sadeq Saba says.
Reports from other major cities suggest that similar harsh measures are being adopted there, he adds.
In the historic city of Isfahan, police recently banned women who were improperly veiled from entering public places, the country's official news agency Irna reported.
It said police in the city also banned the playing of live music in reception halls and at public events.
Since February's victory, Iran's conservatives have been putting pressure on the authorities to fight what they call the erosion of Islamic values, our analyst says.
The hardliners are angry that women are progressively defying the rules by wearing shorter, tighter and brighter coats, especially during the scorching summer months.
But many observers believe that the crackdown will be counter-productive in a country with a young, educated and increasingly rebellious population, our analyst adds.