The Congress leader, however, was only quoting from a book penned by Uddhav's grandfather, Prabodhankar Thackeray, father of Shiv Sena chief Bal Thackeray.

Uddhav admitted that although his grandfather's book, "Mazhi Jeevangatha" (An Autobiography), does mention that the Thackerays' origins trace back to Bihar, it did not refer to his family, but only to the clan of Thakres.

"What he (Prabodhankar Thackeray) has written does not refer to my family, but to the entire Thakre community which lives in Bihar," Uddhav claimed.

Uddhav accused Singh of making "attempts to exploit the issue politically". He was at pains to dismiss the matter, which had come to a head after he had demanded that Bihari migrants entering Maharashtra in search of work ought to be given special permits.

Singh, on his part, has gone hammer and tongs at the Thackerays, flashing copies of the book, first published in 1995 when the Shiv Sena-Bharatiya Janata Party alliance was ruling Maharashtra.

The book, now enjoying wide publicity, has also emerged as a rallying point for anti-Thackeray lobbies.

The Congress leader pointed to sections of the book - highlighted for effect - that told of Maharashtra's numero uno political family and its origins in Bihar.

According to the author, the Thackerays originally hailed from Magadh in Bihar and migrated to Bhopal and later to Pune, in search of employment opportunities.