At least 15 people have died and 27 remain missing in Zimbabwe after an overloaded boat capsized on Lake Kariba, with 77 passengers rescued as authorities intensified a search-and-rescue operation on Tuesday evening.

Zimbabwe’s Civil Protection Unit (CPU) said the boat was carrying 114 registered adult passengers and five crew members when it capsized. Authorities warned, however, that there could have been additional children below ticketing age who were not included in the passenger records.

The vessel had a carrying capacity of 90 people, meaning it was significantly overloaded at the time of the accident.

Mashonaland West Provincial Administrator and CPU head Cecilia Chitiyo said the passenger figures had been established by checking tickets against available accounts.

The CPU said the situation remained fluid as rescue teams continued working in difficult conditions.

The accident has raised concerns about the safety of vessels operating on Lake Kariba, particularly after local Member of Parliament Mutsa Murombedzi shared video footage showing the boat leaving shore before the tragedy.

Murombedzi said the vessel is used by rural communities living around the lake to travel to Kariba town, with the journey reportedly taking about five hours.

The footage showed people on the shore waving as the vessel departed, while some expressed concern over whether the ageing boat would withstand strong waves on the lake.

Lake Kariba, which is shared by Zimbabwe and Zambia, is the world's largest man-made lake by volume. It stretches for more than 200 kilometres and reaches about 40 kilometres at its widest points.

The lake was created in the late 1950s and early 1960s following the construction of the Kariba Dam across the Zambezi River, which flooded the valley and created the vast reservoir.