'I have been a member of the BJP since it was formed (in 1980),' he said.

'I had never imagined that 30 years of my service would have ended this way. It's regretful,' the visibly emotional Jaswant Singh added.

He said he also 'regretted' that the party president informed him about the decision over the phone and not personally.

'I would have stepped down had they informed me in person,' he said.

'I am worried and sad that just one book has led to my expulsion,' he added, wondering what would happen if 'soch, vichar and chintan' (thinking and introspection) stopped in Indian politics.

He, however, said he didn't regret writing the book.

'They (BJP leaders) have not even read it completely.'