Ghana President John Atta Mills has died after being taken ill, the presidency announced on Tuesday, but details of his death remained unclear.

"It is with a heavy heart that we announce the sudden and untimely death of the president of the republic of Ghana," the statement said, adding that the 68-year-old leader of the West African nation died a few hours after falling ill.

Mills took over as Ghana's president in January 2009. He narrowly won the vote in 2008 with a less than one percent margin against a candidate from the party of incumbent John

Kufuor, widely respected for having bowed out following his two terms in office.

In July last year, Mills was nominated to be the ruling party's presidential candidate for December 2012 elections.