Zambia's founding father Kenneth Kaunda is in a "serious but stable condition", a source close to the former president has told the BBC.

The 97-year-old, who served as president from 1964 to 1991, was admitted to hospital last Tuesday with a minor chest infection, and was actually due to be discharged today, the BBC was told.

But his condition changed overnight and became worrying this morning.

He is still breathing on his own and not on a ventilator. But the situation at the moment is concerning - given his age, our source said.

Both Zambia's President Edgar Lungu and South Africa's President Cyril Ramaphosa have urged people to pray for Mr Kaunda.

He is one of the last surviving members of a group who struggled against colonialism in Africa in the aftermath of the Second World War.