"A case has been filed whose defendants are two brothers. They held conferences on such topics as AIDS, which drew the attention of domestic and foreign organisations and NGOs," Tehran's deputy prosecutor Hassan Haddad was quoted as saying by the reformist Etemad newspaper.
Arash Alaei and Kamiar Alaei have worked for many years on HIV/AIDS prevention and treatment in Iran and internationally, and were reportedly arrested in June. Haddad did not confirm if the pair were currently in jail.
"They would organise foreign trips for people and train them. They were aware of what they were doing, and their training was of the nature of a velvet revolution," Haddad said.
Arash Alaei is scheduled to make a presentation in Mexico on Iran's innovative HIV programme, the New York-based Human Rights Watch said.
"A security prosecution office is continuing to investigate the case," Haddad added.
The Iranian judiciary has recently disclosed details on a series of cases involving charges against opposition groups, including those which have links abroad.
The US-based Physicians for Human Rights (PHR) on July 23 expressed concern over the reported detention of the pair and wrote to Iranian President Mahmoud Ahmadinejad, asking that Tehran either charge the brothers or release them.
Last year, the Iranian government jailed two American-Iranians, Haleh Esfandiari and Kian Tajbakhsh, for acting against national security.
Esfandiari, an academic at the Woodrow Wilson Centre in Washington, and Tajbakhsh, a board member of the Centre for Citizen Peacebuilding at the University of California, were freed on bail after more than 100 days in jail.
