Iranian president Hassan Rouhani congratulated Field Medal winning mathematician Maryam Mirzakhani by tweeting a uncovered photograph of her, in a move likely to be seen as a strong political statement.
Mr Rouhani’s tweet, posted last night, showed 37-year-old Iranian-born Mirzakhani wearing a headscarf in one photo (as required by Iranian law) and without in another.
She is the first woman ever to win the Fields Medal, established in 1936.
The president’s congratulations have already been retweeted 2,217 times, with many social media users applauding the Iranian president’s decision. Channel 4 News International editor Lindsey Hilsum said the tweet was “amazing”.
Although women are legally required to wear a hijab in public in Iran, in recent months there has been a flickering online campaign by younger generations to wear lighter, more transparent and looser hijabs – if at all.
Last year Mr Rouhani faced criticised by Iranian right-wing hardliners for his moderate attitudes, saying: "If a woman or a man does not comply with our rules for clothing, his or her virtue should not come under question … In my view, many women in our society who do not respect our hijab laws are virtuous. Our emphasis should be on the virtue."
After his election last year in June, Mr Rouhani has clashed frequently with hardliners as he has sought to take a softer line than that of former Iranian president Mahmoud Ahmadinejad.
Mrs Mirzakhani was born in Tehran, completing her undergraduate maths degree at Sharif University before moving to the United States in 1999 to study at Harvard.
She has previously defended Iran’s education, stating: "I should say that the education system in Iran is not the way people might imagine here," she told Clay Mathematics Institute. "As a graduate student at Harvard, I had to explain quite a few times that I was allowed to attend a university as a woman in Iran."