Zambian President Michael Sata has died in a London hospital. He was 77.

“It is with a heavy heart that I announce the passing on of our beloved president,” government cabinet secretary Roland Msiska announced on Wednesday.

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Msiska said Sata died in London’s King Edward VII hospital, and called for Zambians to remain calm.

Sata hadn’t been seen in public since returning from the UN General Assembly last month, where he failed to make a scheduled speech.

He flew to London just over a week ago for treatment.

Sata made a rare public appearance in Zambia on September 19 to tell the southern African nation’s parliament: “I am not dead.”

When he left for London, he appointed Minister of Defence and Justice Edgar Lungu as acting president.

Despite repeated denials the president was ill, analysts had said a power struggle was already under way behind the scenes for Zambia’s top job.

Supporters who voted Sata into office in 2011 saw him as a no-nonsense man of action, while for critics, the former policeman, trade unionist and taxidermist was an authoritarian populist.