Samajwadi Party leader and legislator Mitrasen Yadav died on Monday after a prolonged illness. He was 85.
A legislator from Bikapur constituency in Faizabad, Yadav was admitted to the Ram Manohar Lohia Institute.
A close associate of party chief Mulayam Singh Yadav, Mitrasen Yadav was elected to the Uttar Pradesh assembly in 1977, 1980, 1985, 1993, 1996 and 2012 and thrice to Lok Sabha.
Chief Minister Akhilesh Yadav visited the ailing leader at the hospital on Sunday night after his condition worsened, an official said.
Both the chief minister and Mulayam Singh Yadav mourned his death and paid rich tributes to him. His cremation will take place in his home town on Tuesday.