ZAMBIAN president Michael Sata has died in London after an illness.

Mr Sata passed away in the King Edward VII hospital, where he was being treated, Cabinet secretary Roland Msiska said.

Mr Sata's wife Christine Kaseba and his son Mulenga Sata were at the side of the 77-year-old president when he died.

"I urge all of you to remain calm, united and peaceful during this very difficult period," Mr Msiska said in an appeal to Zambians.

The cabinet has discussed plans for a political handover and vice president Guy Scott, a white Zambian whose appointment in 2011 caused a stir in the country, has been appointed interim leader.

A presidential election will be held within the next three months and if Mr Scott is elected he will be Zambia's first white leader.

Rumours that Mr Sata was seriously ill had gripped Zambia since the leader largely dropped out of public view months ago, and opposition groups criticised the government for declining to release details about his medical condition.

Since June, the president has made only a few brief appearances and missed a number of summits, including a scheduled speech at the UN General Assembly in New York.

Mr Sata was a long-time opposition leader who became president in 2011 after he defeated the incumbent Rupiah Banda.