The Zambian president had been due to sit next to Mr Mugabe at the AU summit, where seating is arranged alphabetically.

BBC: Zambia president 'suffers stroke'

In 1969, Zambian President Kenneth Kaunda announced nationalization of copper mining companies, key to Zambia's economy contributing over 50 percent of government revenue.

CNN: Tuesday,

"I wish to inform the nation that the president had suffered a stroke, " Zambian Vice-President Rupiah Banda said in a statement.

BBC: Zambia president 'suffers stroke'

Recent Zambian elections teetered on a knife-edge when the opposition won there, before President Rupiah Banda gracefully accepted defeat rather than cry foul.

WSJ: The Real Legacy of Nelson Mandela