A British-Iranian woman held in a Tehran prison since June for going to a men's international volleyball match has gone on hunger strike, her family has announced.
Ghoncheh Ghavami, 25, is believed to be detained in the notorious Evin prison in the Iranian capital.
In an emotional message on a Facebook page created to campaign for Ghoncheh's release, her mother Susan confirmed her daughter's protest move.
"Yesterday, I finally saw my Ghoncheh. She said she's been on a hunger strike since Wednesday. God, I can't breathe,” Susan wrote today.
“It's been a while that she has no more interrogations but her detention has not ended,” Susan added.
The Iranian authorities have not formally charged the woman since her detention on 10 June.
During his meeting with Iranian President Hassan Rouhani in New York last month, the UK Prime Minister David Cameron raised the treatment of dual British-Iranian nationals, in particular the case of Ghavami.
Cameron's office said raising the issue with Rouhani underlines the impact that such cases had on Iran’s image in the UK.
Being a dual national, the FCO has limited ability to help Ghavami.
The UK foreign ministry earlier expressed its concern about Ghavami's detention.
It said: "We are in touch with her family and we have raised our concerns with the Iranian government and asked for more information about her welfare and the charges against her."
"Ghoncheh said that she can't tolerate this any longer and she's on a hunger strike,” her mother said in the Facebook message.
"I will not touch food either until the day that my Ghoncheh will break her hunger strike. God, you've been my witness, I have remained silent for 82 days so that my innocent daughter returns home,” she added.
Amnesty International has called on the Iranian authorities to release the Ghoncheh immediately.
A ban on women attending football matches has been in place since 1979 and in 2012 was extended to volleyball, it said.
The organisation added the ban became a matter of renewed controversy on 13 June, when at a match between Iran and Brazil, Brazilian women were permitted to watch the match and cheer on their team but Iranian women were prevented from doing the same.
A petition set up on online campaigning platform Change.org to appeal for her release has now been signed by more than half a million people.
Last month, Ms Ghavami's brother Iman took the petition to the United Nations in New York.