The family of Mahsa Amini, the Iranian Kurdish woman who died in custody, have been banned from travelling to France to collect a top rights prize awarded posthumously, their lawyer said Saturday.

Amini died aged 22 on September 16, 2022, while being held by Iran's religious police for allegedly breaching the Islamic republic's strict dress code for women.

Her family and supporters say she was killed. Iranian authorities claim she died in custody from a previously undisclosed medical condition.

In October, the European Union awarded its top rights honour, the Sakharov Prize, to her and the global movement her death triggered.

On Saturday her family's lawyer in France, Chirinne Ardakani, told AFP that Amini's parents and brother had been "prohibited from boarding the flight that was to take them to France for the presentation of the Sakharov Prize".

She said the family had been banned from leaving Iran despite having a valid visa, and their passports had been confiscated.

Ardakani said Iranian authorities "have never been so mobilised to prevent the families of the victims from speaking to the international community".

Mahsa Amini's death triggered mass protests in Iran.

It also generated a global movement known as "Woman, Life, Freedom", calling for the end of Iran's imposition of a headscarf on all women and an end to the Muslim cleric-led government in Tehran.

Iranian security forces have cracked down on the protests domestically, killing hundreds, and have executed dozens for allegedly participating in what officials have called "riots".

The "Woman, Life, Freedom" campaign continues in cities around the world, with frequent demonstrations in which Amini's photo is held aloft.

The Sakharov Prize, which comes with a 50,000-euro ($53,000) endowment, was to be handed over in a European Parliament ceremony on December 13.