A survivor from the ill-fated boat MV Spice recuperates at Mnazi Mmoja Hospital in Zanzibar September 10, 2011. [Photo/Agencies]

STONE TOWN, Zanzibar - Nearly 200 people drowned when an overloaded ferry capsized off east Africa as it sailed from Zanzibar to Pemba island, police said on Saturday, Tanzania's worst maritime disaster in at least 15 years.

Fishing boats, tour operators and diving instructors spent the night scouring the sea off the coast of Tanzania looking for survivors, many clinging to strewn cargo. One photo showed two men and a child floating on a mattress, clinging to a fridge.

Zanzibar police spokesman Mohamed Mhina told Reuters 192 bodies had been recovered and 606 passengers rescued from the Indian Ocean so far.

"There is a possibility that more bodies still remain at sea. Rescue workers are still searching for survivors and retrieving bodies," he said.

Two tug boats docked at Zanzibar's port, one carrying 17 bodies and another with 15 bodies, many of them children.

At the northern tip of the island, dozens of soldiers carried bodies onto white sand beaches, where thousands of people anxiously awaited news of survivors.

"The ferry flipped and capsized. There could be more bodies trapped inside the hull of the ship with the cargo," rescue worker Ali Ramadhan told Reuters at the port. "We suspect the ship was overcrowded with more than 800 passengers onboard. It is normal for these ferries to overload passengers and cargo."