Tehran, Iran (CNN) -- Nasrin Sotoud

Tehran, Iran (CNN) -- Nasrin Sotoudeh, a prominent Iranian human rights activist, was among five women activists released Wednesday from a Tehran prison where she had been jailed since 2010.

"I'm glad, but I'm worried for my friends in prison," she told CNN's Christiane Amanpour in a telephone interview soon after her release, citing other political and human rights activists who remain in prison.

Sotoudeh did not learn about her impending freedom until she was driven through the gates of the notorious Evin Prison, which had been her home since she was convicted of acting against national security and other charges

"They told me, 'You're free,'" she said. She has since reunited with her husband, Reza Khandan, and her two children.

Sotoudeh's release comes just days before world leaders, including Iranian President Hassan Rouhani, attend the U.N. General Assembly meeting in New York.

Sotoudeh said she expected to be allowed to continue practicing as a lawyer.

Asked if she considered it to be a new day for Iran, she noted that "many political prisoners" remain in jail. "But I hope that this will be a new day," she said.

In an earlier telephone interview, Khandan said his wife, who is a lawyer, had another three years of her sentence remaining and he had not been told whether her release was final.

But Sotoudeh said that her freedom was not temporary. "Free forever," she said.

Sotoudeh was the attorney for Arash Rahmanipour, one of two men executed by the Islamic republic in early 2010. He was accused of being an enemy of God and belonging to a banned opposition group.