The main Iranian resistance movement in exile condemned on Wednesday a raid by Iraqi forces on their supporters' last main base camp, calling it a "crime against humanity".
"Attacking besieged people with no means of defence is a crime against humanity," Maryam Rajavi, president of the National Council of Resistance of Iran, told a news conference in Rome after riot police clashed with Iranian exiles in the Iraqi town of Ashraf.
The group, which includes the armed People's Mujahedeen of Iran, accuses Baghdad of taking orders from Tehran.
About 100 Iranian exiles demonstrated outside the parliament building in Rome where Rajavi was speaking.
Also Wednesday, some 50 Iranian exiles gathered outside the Iraqi embassy in Paris to denounce Prime Minister Nuri al-Maliki's government, and a similar group demonstrated outside the Dutch foreign ministry in The Hague.
Iraqi officials have said that more than 400 people were injured during a security operation on Tuesday in the Ashraf Mujahedeen camp, and 50 arrests were made. Rajavi claimed that seven protesters were shot dead.
"I ask the American government and those of the European Union to strongly condemn the actions of the regime... The American government must assure the security of the residents of Ashraf," Rajavi said.
Iraqi officials have denied killing anyone, and say that two of their own riot officers died after succumbing to wounds suffered in the clashes.
About 3,500 Mujahedeen and their families have lived in Ashraf since former Iraqi dictator Saddam Hussein allowed the Iranian opposition to set up bases on his territory during his 1980-88 war with Iran.
Following the 2003 US-led invasion of Iraq, American forces disarmed the Mujahedeen in Ashraf but placed the residents under protection. Now, Iraq's increasingly independent government has moved to take charge of the site.
"This aggression is a flagrant violation of international conventions and the assurances given by the Iraqi government to the United States about the protection of the residents of Ashraf," Rajavi said in a statement issued in Paris.
She called on the international community to intervene to prevent what she said would become a "humanitarian catastrophe" and urged Washington to hold its Iraqi allies responsible for the safety of camp residents.
Iranian Supreme Leader Ayatollah Ali Khamenei, a hate figure for the Mujahedeen exiles, is faced at home with angry street protests over his endorsement of last month's re-election of President Mahmoud Ahmadinejad.
The United States said on Tuesday it would "monitor the situation closely to ensure the residents of Camp Ashraf are treated in accordance with Iraq's written assurances that it will treat the residents there humanely."
Baghdad insists that it was merely asserting its sovereignty and the rule of law in retaking control of Ashraf, rather than working for Iran, but Iranian leaders nevertheless welcomed news of the operation.
The protesters in The Hague demanded that the Dutch government condemn the operation and brandished a banner declaring it a war crime.