Robert Mugabe has prostate cancer and has been told by doctors that he could be dead by 2013, WikiLeaks documents have revealed.
Zimbabwe's 87-year-old president was apparently diagnosed with the condition several years ago and warned in 2008 that it could kill him within five years.
Details of his sickness were confirmed in secret U.S. diplomatic cables published by WikiLeaks.
It provides the first confirmation that the end of Mugabe's rule could be in sight.
He was told to stand down amid concerns about his failing health, according to the cables. When his death comes, it is expected to cause a serious internal power struggle.
The documents show that America's former ambassador to Zimbabwe James McGee was informed of Mugabe's condition on June 4, 2008 during a private meeting with Gideon Gono, a close friend and governor of Zimbabwe's reserve bank.
In a cabled summary of the meeting, Mr McGee reported: 'Gideon Gono, governor of the Reserve Bank of Zimbabwe, told the Ambassador on June 4 that President Robert Mugabe has prostate cancer that has metastasised and, according to doctors, will cause his death in three to five years.
'According to Gono, Mugabe's doctor had recommended he cut back on his activities.
'(NOTE: Gono told us last year that Mugabe was ill and that his doctor had urged him to step down immediately. Mugabe had told his doctor, according to Gono, that he would leave office after the election).'
Confidant: Gideon Gono, Mugabe's close friend, apparently told the U.S. diplomat about Mugabe's diagnosis
Mr McGee's cable was entitled 'Ambassador's meeting with Gideon Gono' and sent to Washington from Harare on June 6, a few weeks before 2008's contested Zimbabwe elections.
In his note, the ambassador speculated that given Mugabe's rapidly faltering health, it was likely that even if the aging Zanu-PF leader won the upcoming poll that he would stand down by the end of the following year.
He wrote: 'Given Mugabe's health, and the desire of many within Zanu-PF that he step down because of the state of the economy, it is likely the latest date Mugabe will stay in office, assuming he wins on June 27, is December 2009.
'This is when Zanu-PF will hold its scheduled Congress to re-elect officers.
'It is also quite possible that after a June win, Zanu-PF will begin the succession game resulting in a departure for Mugabe earlier than December 2009.'
The diplomatic cable was marked 'confidential' but published online last week as part of Wikileaks's huge dump of unredacted notes.
The dictator has appeared increasingly frail during recent years and was widely believed to have been suffering from cancer.
This year alone he has made at least five trips to Singapore, where he is believed to be receiving treatment at a top private clinic.
However those around the leader have maintained a wall of silence over his health, and his spokesman has repeatedly claimed Mugabe's hospital visits were to receive treatment for a problem with his eyes.
Today local media in Zimbabwe reported that Gono had denied telling Mr McGee about Mugabe's sickness.
In a brief statement given to the New Zimbabwe website, he said: 'It's a lie. I wouldn't even dare talk about that.'
Despite his illness, Mugabe makes significant effort to ensure he continues to be seen as a powerful figure.
His Zanu-PF party has ruled Zimbabwe since the country gained independence from Britain in 1980.
Since then the Mugabe has been condemned for a litany of human rights abuses and for allowing the economy to collapse.
The two leaders later formed a unity government, with Tsvangirai serving as prime minister since February 2009.
However Mugabe has repeatedly signaled his intention to call fresh elections, and said last week that the country would return to the polls early next year.