By James Mackenzie
Maryam Rajavi, president of the Paris-based National Council of Resistance of Iran (NCRI) said the latest wave of protests should be backed by economic measures by Western governments.
"It's time to adopt very firm, global sanctions," she told Reuters in a telephone interview.
"There needs to be a firm policy to cut economic and political relations because the Iranian people have taken to the streets. They have to be helped. The United States and Europe must act," she said.
The NCRI and its main faction, the People's Mujahideen Organisation of Iran (PMOI), have thousands of followers in Europe and the United States and it was the first group to expose Iran's covert nuclear programme in 2002.
The group, which began as a leftist-Islamist organisation opposed to the former Shah, says it has wide backing in Iran but Western analysts say its support is hard to gauge and is limited because it sided with Iraq during the 1980-88 Gulf war.
Iran's Intelligence Ministry said members of the PMOI were among those arrested in Sunday's protests.
Rajavi said the protest movement was now calling for the same things that her group was aiming for: a complete removal of the government under Supreme Leader Ayatollah Ali Khamenei.
"What the Iranian people want is a total change in the regime of the Supreme Leader. They don't want reform or a more moderate approach from the regime," she said.
"They want to overthrow the regime of the mullahs, they want a secular republic to replace religious dictatorship."
The PMOI was removed from a European Union list of banned terrorist groups in January but it is battling to be taken off a similar U.S. list.
"It's very unfortunate now to have the terrorist label applied to the Iranian resistance movement by Western countries because it's very clear that it was at the request of the mullahs' regime," she said.
"I think Western countries have to be impartial towards the Iranian people and the resistance and the mullahs' regime."
