TEHRAN, Iran (CNN) -- Iran said the gunman who killed Neda Agha-Soltan may have mistaken her for the sister of an Iranian "terrorist," the Islamic Republic News Agency reported Wednesday.

In death, Neda Agha-Soltan has emerged as a powerful symbol of opposition to the Iranian government. more photos »

Iran blamed the death of the woman known to the world simply as Neda squarely on "those groups who want to create division in the nation," saying they planned the woman's killing "to accuse the Islamic republic of ruthlessly dealing with the opposition," according to IRNA, Iran's state-run news agency.

The report said the investigation into her death is ongoing, "but according to the evidence so far, it could be said that she was killed by mistake. The marksmen had mistaken her for the sister of one of the Monafeghin who had been executed in the province of Mazandaran some time ago."

Monafeghin refers to the People's Mujahedin Organization of Iran, or PMOI, which promotes a secular, Marxist government for Iran, and has waged a violent campaign against the fundamentalist Islamic regime, including bombings that killed politicians, judges and Cabinet members.

Also known as Mujahedin-e-Khalq, the group initially was formed to oppose the Shah of Iran but fell out of favor with the Islamic Revolution of Ayatollah Ruhollah Khomeini after 1979.

The European Union removed the group from its list of terrorist organizations this year, prompting outrage from Tehran. The Iranian Foreign Ministry accused the European Union of "making friends and cooperating with terrorists" by removing the group from its list.

Neda, 26, rose to prominence within hours after a crudely shot video documenting her final moments was uploaded to the Web. Shortly after she died Saturday from a single gunshot wound to the chest, she emerged as a powerful symbol of opposition to the Iranian government. See images of Neda and the impact of her death »

"It's heartbreaking," President Obama said Tuesday, referring to the video of Neda, which means "divine calling" in Farsi.

"And I think anyone who sees it knows there's something fundamentally unjust about it."

The Iranian government has sought to minimize the impact of her death. Watch how Neda's death has attracted world attention »

IRNA reported Wednesday that the killer, or killers, may have "thought that they were targeting one of the government opposition people and that is why they immediately distributed the video of the aftermath of the killing through the official and unofficial media in order to reach their murderous objectives against the Iranian government and revolution."

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