NEW DELHI: Efforts by India's Congress party to block the publication of a "dramatised" biography of its president Sonia Gandhi only stoked interest in the book, said author Javier Moro.

The Red Sari, the English translation of the 2008 Spanish-language El sari rojo, hit bookstands in India last week, seven months after the party was ousted after a decade in power.

"I'm thankful, because they gave me a fabulous free publicity campaign," said Moro, speaking in Spanish about the protests against the book at an event in India's capital on Tuesday.

The Red Sari was ranked second among new releases on the Amazon India website's bestseller list on Wednesday.

The Italian-born Gandhi, 68, has played a reduced public role since Prime Minister Narendra Modi and his right-wing Bharatiya Janata Party snatched power from the Congress in May.

Moro said he was surprised there were no books available on the media-shy politician, who rose from obscurity after her marriage into India's Gandhi dynasty and was thrust into the limelight as the widow of an assassinated former premier.

Gandhi took over the reins of a floundering Congress party in 1998 and was the architect of its unexpected triumph in national elections six years later.

In what was seen as a masterstroke in the wake of protests over her Italian birth, she declined to become prime minister, preferring to wield power from behind the scenes.

Moro wrote his book on Gandhi without her consent, calling it the "dramatised" biography of a public figure considered one of the world's most powerful women. Any writer would be lucky to get his hands on material such as Sonia's life, he said.

Congress party leaders had opposed the publication of the book in 2010 and threatened to take legal action. Moro, an Indophile writer like his uncle Dominique Lapierre, said he stayed away from the country after his effigies were burned.

Among parts of the book that riled the Congress was the assertion that Gandhi had considered leaving India after her husband was killed in 1991.

Moro said he did not know if Gandhi had read the book, adding that at their only meeting, she told him that the Gandhis never read what's written about them.

On Wednesday, a Congress leader said the party had never been comfortable with the idea of proscribing books.

"There may be exigencies at times, but we need to find more subtle ways of dealing with it," Manish Tewari told Reuters in a text message.

Despite the "incomprehensible" delay to publish a book he says contains nothing offensive, Moro's faith in the freedom of expression in India has not been shaken.

"There is a free press, there is free expression," he said, warning that in any democracy, vigilance was needed to protect free speech.

The 59-year-old writer, who won Spain's highest literary award in 2011, said he would never again write about a living person as it was too much trouble.

"I'll write about people who have been dead for a long time," Moro said. "And whose lawyers are also totally dead."