In a column entitled "I'd rather not be Anna" published in The Hindu newspaper, the novelist, essayist and rights activist condemned both the style and substance of Hazare's campaign that has mobilised public opinion in India.
In particular she questioned Hazare's use of the hunger strike and other tactics and symbols co-opted from his hero -- India's independence icon Mahatma Gandhi.
"While his means may be Gandhian, Anna Hazare's demands are certainly not," Roy said.
The focus of Hazare's protest is a new anti-corruption bill.
The 74-year-old activist says the current draft is too weak and wants parliament to pass his own version which gives more scope and power to an ombudsman who would monitor politicians, bureaucrats and the judiciary.
While agreeing that the government bill was so flawed "that it was impossible to take seriously", Roy said Gandhi would have been dismayed by Hazare's vision of an all-powerful, centralised ombudsman.
Hazare, who has not eaten for six days and took his fast public on Friday, has drawn huge crowds to the open air venue where he is staging his hunger strike in central Delhi.
The atmosphere is one of celebratory protest, with the crowds singing along to patriotic songs and waving the Indian national flag.
But Roy, a vocal government critic, said she was dismayed by "the props and the choreography, the aggressive nationalism" of the Hazare movement.
"They signal to us that if we do not support the fast, we are not 'true Indians'," she said.
"Who is he really, this new saint, this Voice of the People?" she asked, accusing Hazare of remaining silent on other issues like farmers' suicides in his home state of Maharashtra.
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