So far the page has around 150 photos. They show women on the beach, on the street, in the countryside, alone, with friends or their partners - but crucially - all without the headscarf. Most include a few words, for example: "I loathe the hijab. I too like the feel of the sun and the wind on my hair. Is this a big sin?"

Ever since the Islamic Revolution 35 years ago, it has been illegal for a woman to leave the house without wearing a headscarf. The punishment ranges from a fine to imprisonment. "My hair was like a hostage to the government," says Masih Alinejad, an Iranian political journalist who lives in the UK and who set up the Facebook page. "The government still has a lot of hostages," she adds.

Alinejad got the idea after she posted some photos of herself without the hijab to her own Facebook page. The images were liked thousands of times. So many women began to send her their own pictures that she decided to set up a dedicated page. Though she's well-known for being critical of the government in Iran, she insists the page is not political. "These are not women activists, but just ordinary women talking from their hearts."

"My problem is not having to wear the headscarf. My problem is not having a choice," writes one woman on the Facebook page. "Stealthy freedom means, just for a few seconds, I will be what I want to be," writes another.

The hijab is a controversial issue in Iran. A recent billboard campaign reminding women to cover themselves up, was mocked on social media for comparing women to chocolates in a wrapper. But many support the wearing of the hijab, arguing it's an important part of Islamic law - there was a demonstration in Tehran last week, with protesters calling for a more strict implementation of the rules.