By Miranda Eeles
BBC Tehran correspondent
A gathering to celebrate International Women's Day in Tehran turned ugly as militia groups broke up what had started as a peaceful demonstration.
Demonstrators called for freedom and justice for women
Members of the Basij volunteer group beat people with batons and pushed several men and women to the ground.
The authorities had tried to cancel the demonstration, withdrawing permission just hours before it was due to begin.
Shouting slogans and singing freedom songs, several hundred women defied the ban and gathered in Laleh Park.
They had come to hear local activists' speeches on violence against women, to commemorate International Women's Day.
"We were supposed to perform different plays," said one local woman, "to show how women are exposed to violence and to show how women's voices are not heard."
"Now they won't even let us speak," she added.
Dozens of police stood by, refusing to let the crowd congregate and ordering them to go home.
After the organisers left, members of volunteer militia groups, the Basijis, arrived, some on motorbikes, others brandishing batons.
They tried to intimidate the crowd of men and women who remained behind.
There are reports that several people were arrested.