The Taliban's treatment of women and girls in Afghanistan is a "crime against humanity", Gordon Brown has told the BBC.
The former prime minister is calling on the International Criminal Court (ICC) to prosecute those responsible for the "vicious" abuse of human rights.
The Taliban government has severely restricted the freedoms of women and girls since regaining power in 2021. "This is the systematic brutalisation of women and girls," he said.
Speaking to BBC Radio 4 Today's Nick Robinson, Mr Brown, now the UN's special envoy for global education, said: "They've been excluded from education, excluded from employment, excluded from visiting public places.
"All these bans are a form of discrimination. It's probably the most heinous, most vicious, most comprehensive abuse of human rights in place around the world today."
He said some described the system as a form "gender apartheid", and that it should be considered a crime against humanity.
"It's right then for the International Criminal Court, which has responsibility for dealing with crimes against humanity, to both investigate and prosecute those responsible."
The ex-Labour prime minister, who led the UK from 2007 to 2010, suggested the pressure of a potential prosecution could force the Taliban to reconsider, and said he was shocked by there was "so little international pressure on the regime".
Mr Brown also called for UK sanctions against the Taliban leadership, and leaders and clerics from Muslim-majority countries to help persuade them that "Islam is a religion that values women and girls".
The UN has described women reporting feeling isolated and living in prison-like conditions
The former prime minister's intervention comes as the two-year anniversary approaches of the fall of the democratic government and Taliban takeover following the withdrawal of Western troops.
Taliban leaders promised a more moderate rule than during their previous period in power from 1996 to 2001.
Last month Afghan women held a rare protest against the Taliban's decision to shut female beauty parlours and salons.
Girls have been banned from attending secondary school and women excluded from university.
Women and girls are also prohibited from entering amusement parks, gyms and working in non-governmental organisations, and must adhere to a strict dress code.
The UN has previously said women reported feeling "invisible, isolated, suffocated, living in prison-like conditions", with many unable to meet and their basic needs without employment or aid.
Around 40% of the country's 40 million people suffer acute food insecurity, according to the IPC scale that measures levels of malnutrition.
Fereshta Abbasi, a researcher for Human Rights Watch, said on Thursday that Afghans were "living a humanitarian and human rights nightmare under Taliban rule".
She called on Taliban leaders to "urgently reject their abusive rules and policies" and implored the international community to hold them accountable for the crises their country faces.