Ms Nasreen, who now lives in Sweden, told the BBC she had no idea that a case had been filed against her, or that a trial was taking place.
On Sunday, a magistrate's court gave her a one-year prison sentence on a charge of writing derogatory comments about Islam in several of her books.
This is the first sentence against the writer who was forced to flee the country in 1994 after receiving death threats from Muslim extremists.
Taslima Nasreen's criticism of traditional Islamic values and customs angered many hardline Islamic groups in Bangladesh.
Muslim sentiment
In 1994, one of the groups put a price on her head after she reportedly called for a revision of the Koran to give more freedom to Muslim women.
Ms Nasreen has denied making any such comment.
She was tried in her absence in a magistrate's court in Gopalganj, nearly 100 kilometres (60 miles) from the capital Dhaka.
The case was filed by a hardline Islamic leader, Mohammad Dabiruddin, who heads a local religious school.
Mr Dabiruddin accused Ms Nasreen of writing offensive comments about Islam - and magistrate Shah Alam found her guilty of hurting the sentiments of Muslims.
In 1994 Prime Minister Khaleda Zia's government charged Ms Nasreen with blasphemy over some of her controversial comments.
Life in exile
Ms Nasreen fled after being granted bail in the case and has since been living in exile - mostly in France and Sweden.
In 1998 she returned to Bangladesh to visit her ailing mother, but left the country after her death.
The Bangladeshi Government has already banned three of her books - Shame, My Childhood and Wild Wind.
The government said the books might hurt the people's religious sentiments.
Senior lawyers say that in order to appeal against the verdict, Ms Nasreen must first surrender before the trial court.