Tens of thousands of supporters of the Iranian opposition have attended a rally in France organised by the National Council of Resistance of Iran.
It is calling for the lifting of international bans on their movement's armed wing, the People's Mujahideen.
The US and the EU list the wing as a terror organisation, although Britain lifted its own ban in the past week.
The Iranian opposition leader said banning the People's Mujahideen played into the hands of Iran's government.
Organisers said 70,000 people from across Europe attended the rally at an exhibition centre in the northern Paris suburbs, though there was no independent confirmation of the number.
Among those present were delegations from several European parliaments.
No legal justification
They heard an address from the Iranian opposition leader, Miriam Rajavi, calling on the European Union to remove the designation of "terrorist group" that it applies to the People's Mujahideen.
The EU and the United States both say that the People's Mujahideen - which took up arms against the Islamic republic in the 1980s and had sanctuary in Iraq under Saddam Hussein - falls under the definition of foreign terrorist organisation.
However the group's supporters say it has long since abandoned attacks that can be called terrorist, and argue that the ban in Brussels and Washington is intended to curry favour with Tehran.
This week the People's Mujahideen achieved a major breakthrough, when it was dropped from a list of terrorist organisations in Britain, and supporters now say there is no legal justification for maintaining the European ban.
France, which takes over as president of the European Union on 1 July, will have to decide whether to respond to the appeal.