He was 79.
Singh, a close confidant of Indira Gandhi and Rajiv Gandhi, was ailing for the last few days, family sources said.
He was elected from Gaura Assembly segment for the first time in 1962 as an Independent candidate.
Singh joined Congress in 1966 and was elected to the Uttar Pradesh Legislative Council in 1967. He became a Lok Sabha MP from Barabanki in 1971.
