A Montreal-based university professor being held in an Iranian jail is now reportedly facing charges, but her relatives say they haven't received word about the nature of any accusations.

Iran's semi-official ISNA and Tasnim news agencies said Monday that Homa Hoodfar has been indicted on unknown charges.

They quoted Tehran's prosecutor as saying Hoodfar was among three dual nationals and a foreigner who had been charged.

The four, who have ties to Canada, Britain and the United States, are all believed to have been detained by hardliners in Iran's paramilitary Revolutionary Guard.

Amanda Ghahremani, Hoodfar's Montreal-based niece, said in an email relatives have only heard the same news reports as everyone else and that they would not comment until further details are available.

"While the prosecutor makes this announcement through the media, neither Homa's lawyer nor her family have been informed of the actual charges against her and so the family would rather wait until we have specific details before making a comment," Ghahremani wrote Monday.

The family had said in late June the Iranian probe into Hoodfar centred on her dabbling in feminism and security matters.

Hoodfar, a 65-year-old professor at Montreal's Concordia University, was born in Iran but has been living in Montreal for 30 years.

She is an anthropologist who has conducted research on Muslim women in various regions of the world.

Her family said she travelled to Iran in February to see family and conduct academic research.

Hoodfar was initially arrested in March, shortly before she was to return home, but was released on bail. She was rearrested June 6 and is being held at Tehran's notorious Evin prison.

Canada's Global Affairs Department said it remains "actively engaged" in Hoodfar's case, is in contact with her family and is working closely with "like-minded allies" to help the imprisoned academic.

"We are aware of media reports pertaining to charges being laid against Dr. Hoodfar," it said in a statement. "Consular officials are seeking to confirm these reports."

Privacy concerns mean the federal government's role can't be divulged, the statement added.

Hoodfar's relatives are concerned about her health and safety, while Amnesty International Canada said news of the indictment is cause for concern.

"I think it's very troubling that they are clearly going forward with legal action against Professor Hoodfar," Alex Neve, secretary general of the organization, said from Ottawa.

"We have made it very clear we consider her to be a prisoner of conscience and that she should be released immediately."

Apart from Hoodfar, the three others indicted Monday are:

-- Siamak Namazi , an Iranian-American businessman who has advocated for closer ties between the two countries and whose father is also held in Tehran;

-- Nazanin Zaghari-Ratcliffe , an Iranian-British woman who works for the Thomson Reuters Foundation, the charitable arm of the news agency; and

-- Nizar Zakka, a U.S. permanent resident from Lebanon who has done work for the American government.

 With files from The Associated Press