Divers were on Saturday (Sep 22) searching for survivors in the sunken wreck of an overcrowded ferry that capsized on Lake Victoria, Tanzania, as an official said the death toll from Thursday's disaster had risen to 161.

Rescue workers retrieve a body of a child from the water after a ferry overturned off the shores of Ukerewe Island in Lake Victoria, Tanzania September 21, 2018. REUTERS/Stringer

Four navy pers went inside the MV Nyerere early on Saturday after hearing sounds that suggested signs of life.

Their initial search failed to locate survivors, while bodies continued to float to the surface around the vessel.

State broadcaster TBC said the number of dead stood at 161, citing John Mongella, commissioner for the Mwanza region where the disaster occurred.

The ferry sank on Thursday evening just a few metres from the dock on Ukerewe, the lake's biggest island. Initial estimates suggested there were more than 300 people on board.

On Friday President John Magufuli ordered the arrest of those responsible for the sinking.

In a speech broadcast on TBC One public television, Magufuli said "It appears clear that the ferry was overloaded," adding that "negligence has cost us so many lives ... children, mothers, students, old people".

"I ordered the arrest of all those involved in the management of the ferry. The arrests have already begun," he added.

The president declared four days of national mourning while saying at least 131 people had died, updating an earlier death toll of 126.

Magufuli also announced the government would cover the funeral expenses of the victims.

Mwanza governor John Mongella had earlier said the number of survivors was 40, but it was unclear whether any new survivors had been found since rescue operations resumed with police and army pers on Friday morning.

"Operations are continuing," he said, but hopes are fading that more survivors might still be found.

With a surface area of 70,000 square kilometres (27,000 square miles), oval-shaped Lake Victoria is roughly the size of Ireland and is shared by Tanzania, Uganda and Kenya.

Capsizes are not uncommon in the massive lake, and the number of fatalities is often high due to a shortage of life jackets and the fact that many people in the region cannot swim.

The deadliest such accident in recent decades was in May 1996, when around 800 people died after their ferry sank on the way to Mwanza in Tanzania./.

VNF/Reuters