Fateme Maleki made the announcement in an open letter published on April 28 on opposition websites, including Kaleme.
She later told RFE/RL, "When we last met on March 18, he told me that he shall now refuse meals and would no longer meet anyone or make contact by telephone."
Maleki said Nourizad went on hunger strike because the prosecutor and judiciary have ignored complaints he filed in late autumn. In those complaints Nourizad said his interrogators assaulted him and that they and a judge verbally insulted his family.
“He has personally filed these complaints with the prosecutor from within the prison, but the authorities have ignored them for the past six months," Maleki said.
Nourizad was detained in December 2009 after publishing several open letters critical of Supreme Leader Ayatollah Ali Khamenei.
He was sentenced to 3 1/2 years in prison and 50 lashes on charges of insulting the supreme leader and spreading antistate propaganda.
He was released on bail in June last year but was returned to Evin prison two months later after he wrote another open letter critical of Khamenei.
Maleki said she was unaware of Nourizad's condition as well as whether the prison management had shown a reaction to his hunger strike.
She said Nourizad was suffering from severe dental problems resulting in the loss of some teeth, as well as kidney and skin conditions.