At least 44 people died when the passenger ferry sank between two islands in Lake Victoria on Thursday.
Emergency teams were dispatched to the scene but have halted rescue operations until dawn on Friday, Ukerewe District Commissioner Colonel Lucas Magembe told Reuters.
The higher death toll was given to the Citizen newspaper by John Mongella, regional commissioner for the port of Mwanza on the coast of Lake Victoria, where the MV Nyerere sank on Thursday afternoon.
However, it was hard to establish just how many passengers there were as the person dispensing tickets drowned with the machine recording the data.
The ferry had been travelling between the islands of Ukara and Bugolora and capsized near the area of Mwanza, the agency said.
The ferry according to reports was overloaded with more than about 500 people on board.
The ferry was also carrying cargo when it capsized close to the dock.
Temesa Spokesperson Ms Theresia Mwami said the exact number of casualties had not yet been established.
The year before, nearly 200 people died in another major incident off the coast of Zanzibar.
Such passenger ferries often carry hundreds of people and are overcrowded.
Boats on Lake Victoria are often packed with too many passengers.
- There was no incident reported to the operator, Tanzania's Electrical and Mechanical Services Agency (Temesa), in the course of journey, officials say.
In 2012, 145 people died when a ferry sank off the shore of Tanzania's Indian Ocean archipelago of Zanzibar.