Ashim Ghatak, aged about 70 years and a senior advocate of Asansol sub-divisional magistrate court, had gone to Bhotapuri ghat to pay obeisance to his ancestors, a ritual on Mahalaya day at around 3 pm, Hirapur police said.
He slipped and fell into the river and is missing since then, the police added.
Ghatak is the elder brother of West Bengal labour and law minister Moloy Ghatak.
The disaster management team, fire brigade and police rushed in and launched operation to find him. The minister is himself at the spot to supervise the search.