Jaswant Singh praised Mr Jinnah in his book

A former leader of India's opposition Hindu nationalist Bharatiya Janata Party (BJP) has challenged the decision by an Indian state to ban his book.

The BJP government in Gujarat banned Jaswant Singh's book on Pakistan's founder, Mohammed Ali Jinnah.

Mr Singh has filed a case in the Supreme Court challenging the ban. He was expelled from the party last week.

The state said it banned the book for "defamatory references" to India's first home minister Vallabhbhai Patel.

The late Mr Patel is a political icon in his home state of Gujarat.

Described often as the "Iron Man of India", Mr Patel played an important role in the country's independence and the integration of the different states in the Indian union.

Jaswant Singh said he was "saddened" by the ban.

"The day we start banning books, we are banning thinking," he said.

The book examines the role of Congress party leader and the country's first Prime Minister, Jawaharlal Nehru, and Mr Patel in the partition of India in 1947.

Mr Singh writes that Mr Patel was "far off the mark" in many ways with his projections about the division and future of India.

The BJP dissociated itself from the book and sacked Mr Singh from the party.

Jaswant Singh is a 71-year-old party veteran who has served as finance and external affairs minister in BJP cabinets.

The book has been selling well both in India and Pakistan.