The footage was remarkable: black-clad women swirling swords, performing backflips and running up walls in gravity-defying stunts that could have graced any Matrix movie.
The Reuters video story showed how Iranian women are seeking empowerment and sexual equality through sports. The only problem was the report's headline mistakenly described the peaceful Iranian students of the Japanese martial art of Ninjutsu as "assassins".
It was a costly error.
Although Reuters later corrected the headline, Iranian authorities on Thursday suspended the press accreditation for its 11 staff in Tehran. It was a serious blow to the British news agency because Iran's disputed nuclear programme is a major news story.
A day earlier some of the female Ninjas told Iran's English language Press TV they were filing lawsuits against Reuters for defamation. The thrust of their complaint was they had taken up the sport to keep fit, but had been tarred as potential killers primed to defend the Islamic republic against western and Israeli invaders.
One woman said the February 16 Reuters report could damage the women's chances to participate in international tournaments because "Reuters is considered by many to be a reliable source". Raheleh Davoudzadeh told Press TV: "We want the whole world to know that Reuters has lied about us."
The spat highlights Iran's sensitivity about its image and its suspicions that western media are determined to portray Iran as backward and violent. Iran is particularly paranoid about Britain, which it brands as a "colonial old fox" that pulls the strings of the "Great Satan" America.
But the Iranian regime also has exploited the Reuters report to crack down on the few non-Iranian journalists still working in Tehran, some analysts said.
Iran's nimble women Ninjas were first featured in a Press TV broadcast on January 29 and posted online four days later. The irresistible footage was swiftly snatched up by some British newspapers such as the high-circulation Daily Mail, which invited readers on February 6 to "Meet Iran's Female Ninja Assassins".
As Israel "steps up pressure on Iran over fears the country is building nuclear weapons, these lethal ninjas could be called upon to represent their country if relations descend into military conflict," the newspaper said.
It was another 10 days, however, before Reuters picked up the story with its own video and slide show. Its headline read: "Thousands of female Ninjas train as Iran's Assassins."
After a complaint by the women's Ninjutsu school, Reuters corrected the headline to read: "Three thousand women Ninjas train in Iran."
The news agency insisted there was no malicious intent behind its mistake. "We acknowledge this error occurred and regard it as a very serious matter. It was promptly corrected the same day it came to our attention," Reuters editor-in-chief, Stephen J Adler, said on Thursday. "In addition, we have conducted an internal review and have taken appropriate steps to prevent a recurrence."
Reuters, he added, was in discussions with Iranian authorities to restore the accreditation of its staff in Tehran.
Press TV, which has spearheaded the blowback against Reuters, is viewed as Iran's propaganda mouthpiece in the West.
Ofcom, Britain's independent media watchdog, revoked the channel's licence in January for failing to pay a record £100,000 fine for broadcasting an interview with a prisoner obtained under duress.
Unlike Press TV, Reuters enjoys an excellent reputation for accuracy and impartiality. It had managed to maintain its bureau in Tehran after Iran's disputed presidential elections in June 2009 which was followed by a crackdown on Iranian journalists. Visas for western reporters have since been very hard to come by. The activities of those allowed in on rare visits are strictly monitored and curtailed.
Writing on his EA WorldView portal, Scott Lucas, an Iran expert at Birmingham University in England, said Tehran's measures against Reuters represented a "significant victory" for a regime trying to shield itself from public scrutiny of its economic tensions and political infighting.