Ahari has been held in Tehran's Evin prison since December 2009 on charges of waging war against God (moharebeh), endangering national security, and antistate propaganda. If found guilty, she could face the death penalty.
The global advocacy group Human Rights Watch, the American Islamic Congress, and the National Iranian American Council have all issued calls for Ahari's release in recent days.
Faraz Sanei of Human Rights Watch told RFE/RL on September 2 that concern over Ahari's case is growing. He described the situation as "critical."
Sanei said the Iranian judiciary also claimed Ahari has links to the banned Mujahedin-e Khalq Organization. But he believes the main reason for the charges brought against her is her human rights activities.
"Shiva is a member of the Committee of Human Rights Reporters, and as you know a few members of this committee were arrested following the June 2009 presidential election in Iran, and others fled the country, Sanei said, adding that Ahari's colleague Kouhyar Goudarzi was also in Evin prison.
On September 1, the American Islamic Congress named Ahari the recipient of its first Advocate Behind Bars award.
The award is given to outstanding civil-society activists who have demonstrated leadership, had an exceptional impact, and are unjustly imprisoned.
"Shiva Nazar Ahari is a courageous advocate for human rights and an inspiring role model for women in the region," American Islamic Congress Executive Director Zainab al-Suwaij said.
Suwaij urged the Iranian authorities to release Ahari immediately and drop all charges against her.