Masoumeh Ebtekar is closely aligned with the reform movement, and spent eight years in the cabinet of Mohammad Khatami. (AP)

TEHRAN – Iran’s most influential female political figure, Masoumeh Ebtekar, was to address the faithful at Tehran’s weekly Friday prayer session, which would have added to her list of groundbreaking accomplishments in this male-dominated society.

But late Thursday, her appearance at one of the Islamic Republic’s most enduring conservative institutions was cancelled without much explanation other than that, according to the head of Tehran’s Friday Prayer office, she wasn’t feeling well.

On her Facebook page, however, Ebtekar wrote that her speech was scheduled and had been confirmed. She felt compelled to notify the public, though, that it may be cancelled against her wishes, as reports in the domestic media began to surface.

Some of them suggested that more conservative authorities were opposed to her presence.

Since 1979, Tehran’s weekly Friday prayer sermons have been the apex of Iran’s unique marriage of religion and politics, providing a pulse on the issues of the moment and usually a heavy dose of anti-American propaganda. It’s where the “Death to America” chant can be most often heard.

It has also been a platform to discuss critical issues facing Iranian society, and the scene of pivotal moments in the country’s history.

The format — and its conservative sentiment — has changed little over the years. For decades, no matter the weather, sessions were held in an open-air auditorium at Tehran University, with audiences segregated and women seated far from the speaker.

This winter, to protect attendees from the cold, the sessions are being held at the Mosalla mosque, a vast indoor space often used for political rallies.

Although speakers tend to be conservative establishment leaders, Friday prayer organizers say they do not take sides.

Sayyed Yadollah Shirmardi, head of Tehran’s Friday Prayers Headquarters, responded to criticisms last month about allowing one of Ahmadinejad’s former ministers to speak.

“We select speakers based on current situations, expediency of the country and requests from the public,” Shirmardi said. “Sometimes they are governmental officials and sometimes from other areas, or specialists in certain fields. We invite those who have something to say, and it is not important which political faction they are from.”

Narges Bajoghli, a New York University doctoral candidate conducting research in Iran on the state media, said some in the political elite understand the need to appeal to a wider audience, and that having a female speaker would have been an “important tip of the hat” to female supporters of the ruling establishment.

But the decision to cancel Ebtekar’s speech, which was going to address Tehran’s massive air pollution problem, may have had more to do with Ebtekar’s political affiliations than her gender.

Ebtekar, besides being Iran’s most recognized champion for environmental causes, is closely aligned with the reform movement, and spent eight years in the cabinet of reformist president Mohammad Khatami.

Like many in that camp, she was marginalized during the Ahmadinejad year and was even disqualified as a candidate for Tehran city council in last June’s election.

Ebtekar became internationally known as the official spokesperson of the hostage-takers at the U.S. Embassy in Tehran. Referred to sarcastically as “Sister Mary” by Americans, she appeared on U.S. television news speaking in English with a flawless American accent, which she attained as a child living in Philadelphia while her father studied at the University of Pennsylvania.