A former senior leader of the Hindu nationalist Shiv Sena has launched a new political party in the western Indian city of Mumbai (Bombay).
Analysts say the family split will hit Shiv Sena votes
Raj Thackeray, a nephew of Shiv Sena founder Bal Thackeray, quit the party last December.
He had had differences with his cousin, Uddhav, the executive president of Shiv Sena and Bal Thackeray's son.
Observers expect the new party, the Maharashtra Navnirman Sena, to weaken support for Shiv Sena in the state.
The party's political agenda will be revealed at its first public rally which will be held in Mumbai, capital of Maharashtra state, on 19 March, Raj Thackeray said.
A large number of supporters attended the party's launch, many of whom were former Shiv Sena workers who quit the party soon after Mr Thackeray.
Analysts expect the new party to go back to the original grass root policies of Shiv Sena, which fought for rights for native Maharashtrans before adopting a Hindu nationalist agenda.