Iranian-born French researcher Fariba Adelkhah and Australian university lecturer Kylie Moore-Gilbert reportedly began refusing food on December 24.
Their protests were reported by the New York-based Center For Human Rights In Iran and Sciences Po’s research center CERI, where Adelkhah works.
CERI quoted an open letter by the two women as saying that they had been subjected “to psychological torture and numerous violations of our basic human rights.”
Adelkhah, an anthropologist who has authored several books on Iran, was reportedly detained in June on espionage charges.
Another researcher from Sciences Po in Paris, Roland Marchal, is also incarcerated in Iran.
Moore-Gilbert, a University of Melbourne Middle East scholar, has been in Iranian custody since October 2018. She was sentenced to 10 years in jail for espionage.
Iran has arrested dozens of dual nationals in recent years on espionage charges that they and their governments say are groundless.
Iranian authorities have not provided any solid evidence to back their claims.