"Nitish is 100 per cent untruthful .... He did not fulfil promises made to me for development of Seemanchal districts," Taslimuddin told reporters to justify his decision to quit JD(U) and return to RJD.
Taslimuddin had quit RJD ahead of 2010 assembly polls and joined JD(U) which rewarded him by giving ticket to his son from Jokihat assembly constituency in Araria district.
Asked about the future of his son and the JD(U) MLA Sarfaraz Alam, the former Union minister said he was an adult and capable of deciding for himself.
Welcoming him back into RJD, its national president Lalu Prasad described Taslimuddin as an old warhorse and secular person and said his joining would boost the prospects of the party in the run up to future elections in Bihar.
Taslimuddin, who was a minister in the United Front government headed by H D Deve Gowda, vowed to work hard to vanquish the NDA government in the next assembly polls and bring RJD back to power.