Police say at least 26 people have died, most of them children, when a ferry capsized in the southern African country of Zambia.

Among the drowned were parents and school children aged from six to 15 years, as well as a baby.

The children were travelling to another school across Lake Kariba, in the south of the country, where they were meant to participate in Zambia's 50th independence day celebrations.

Authorities say the accident was caused by overloading. The boat carried twenty people more than its capacity allowed.

Zambia's vice president Guy Scott visited the area on Saturday expressing his condolences to the families of the deceased and saying the government would shoulder the funeral expenses.

Military and police divers have been sent to the lake to retrieve the bodies.