Ghana's President John Atta Mills, who won international praise as leader of a stable model democracy in Africa, died suddenly on Tuesday and will be succeeded by his vice-president in the West African oil, gold and cocoa producer, officials said.
Mills was 68. The unexpected death of the leader of the world's Number two cocoa grower comes months before he was due to stand for re-election in December.
Ghana, also a major African gold producer, started pumping oil in 2010 and posted double-digit growth in 2011, burnishing its image as an increasingly attractive investment destination on the continent. It was praised for its healthy democracy.
"It is with a heavy heart ... that we announce the sudden and untimely death of the president of the Republic of Ghana," a statement sent to Reuters by the president's office said.
Vice President John Dramani Mahama would be sworn in to replace Mills under Ghana's constitution, officials said.
The president's office said that Mills, who celebrated his 68th birthday on Saturday, died a few hours after being taken ill, but no further details were given.
A presidential aide, who asked not to be named, said the president had complained of pains on Monday evening and died early on Tuesday afternoon when his condition worsened.
Mills had returned from medical checks in the United States a few weeks ago.
Ghana's election commission said December's presidential and parliamentary elections would go ahead as planned.
"The election calendar remains unchanged - it's purely a party matter," election chief Kwadwo Afari-Gyan told Reuters, explaining that it was up to the ruling National Democratic Congress (NDC) to find a candidate to replace Mills.
Kenya's President Mwai Kibaki sent a message of condolence to the people of the Republic of Ghana following the death of President Atta Mills.