Protests engulfing Iran have reached a point of "no return" as demonstrators demand wide reforms beyond the end of mandatory hijab rules, said British-Iranian charity worker Nazanin Zaghari-Ratcliffe, who spent six years detained in Tehran.
She said the government's crackdown on the popular revolt and shutdown of the internet showed it was scared of losing control.
"The anger has been building up for many, many years," said Zaghari-Ratcliffe as demonstrations raged for a sixth week, triggered by the death in police custody of 22-year-old Mahsa Amini after she was accused of wearing her headscarf improperly.
"We can see a coming together for one single goal, and that is freedom. The protests are really, really powerful this time. I don't think we've ever seen the unity we're seeing now," said Zaghari-Ratcliffe, describing Amini's death as the "spark for an explosion".
The protests have grown into one of the boldest challenges to the regime since the 1979 revolution even if they do not appear close to toppling a government that has deployed its powerful security apparatus to quell the unrest.
"There is a generational shift which plays a massive role in the new movement," said Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation as a project manager and will address the charity's annual Trust Conference on Wednesday.
"This is the generation of social media and TikTok and the internet. They know more about the world and their rights than we did. They have a lot more courage than we did."
The uprising has seen women tear off and burn their veils, with crowds calling for the downfall of Supreme Leader Ali Khamenei.
Thousands have been detained by security forces and more than 200 killed including children, according to rights groups.
Zaghari-Ratcliffe, 43, was arrested at Tehran airport in 2016 after a trip to see her parents with her then 22-month-old daughter Gabriella.
She was separated from her daughter, whom she was still breastfeeding, and put in solitary confinement in a tiny windowless cell.
Zaghari-Ratcliffe was later convicted of plotting to overthrow the clerical establishment. She denied all the charges against her and the case was widely seen as political.
She was freed in March with another dual national, Anousheh Ashouri, after Britain repaid a historic debt to Tehran.
During her detention in Tehran's Evin prison, Zaghari-Ratcliffe said she met many women who had received long jail terms for protesting against Iran's mandatory hijab rule, including one 19-year-old sentenced to 24 years.
She said the current protests were a greater threat to the regime than previous ones because they had attracted broader support, with labor unions now organizing strikes which could potentially paralyze the economy.
"There's no return from here," she said. "This is not just about forced hijab any more. It's also about the repressive rules they've been imposing on people for a very, very long time. It's about unemployment, it's about lifestyle, it's about freedom to have access to information and the internet."
Iran has shut down the internet and blocked access to platforms such as Instagram and WhatsApp to stop people organizing protests and sharing images with the outside world.
"Shutting down the internet is exactly what they are doing when they put people in solitary (confinement), only on a bigger scale," said Zaghari-Ratcliffe.
"They disconnect you from the outside world so the world doesn't know what is happening to you and you can't tell them. They want people to be scared and feel forgotten."
Zaghari-Ratcliffe said she would continue to speak up for other detainees, including UK-born environmentalist Morad Tahbaz who was expected to fly back to Britain with her in March but was kept behind at the last moment.
He was released on bail with an electronic tag in Tehran in July.
"My story is the story of many people in Iran who remain in prison. I've got the responsibility to be their voice," said Zaghari-Ratcliffe, adding that the protests made her proud to be an Iranian woman.
"It's a shame for those of us living in enforced exile that we cannot be with the women on the streets, but we are certainly very proud," she said.
Zaghari-Ratcliffe is settling back into London with her daughter and husband Richard, who ran a long campaign for her release including a three-week hunger strike while camped outside the Foreign and Commonwealth Office.
But she said she could not feel entirely free while friends were still in jail.
"Freedom is a very relative concept. I'm free in terms of coming out of prison and coming back home to my family in London. But I have left a part of me in Iran," she said.
"I won't be completely free until my country is free."