Quami Ekta Dal (QED) founder Mukhtar Ansari, his brothers, Sibgatulla and Afzal, and son Abbas joined Bahujan Samaj Party on Thursday.
Announcing their induction into the BSP in Lucknow, party chief Mayawati defended the move saying that the allegations against the jailed leader have been not been proven so far.
Four-time MLA Mukhtar Ansari, who is currently lodged in Lucknow jail, will contest from the Mau assembly constituency on Bahujan Samaj Party (BSP) ticket in next month's polls.
Ansari's son Abbas and brother Sibgatulla have also joined the party and they will be contesting the elections from Ghosi and Mohammadabad assembly constituencies respectively.
Mukhtar had earlier won a seat from Mau in 1996 on a BSP ticket.
Last year, Ansari's party had merged with the ruling SP, but the merger did not last long as Uttar Pradesh chief minister Akhilesh Yadav was unhappy with the move.
(With inputs from agencies)