The 88-year-old, who is believed to be suffering from prostate cancer, flew to Singapore by private jet on Saturday for treatment.
His wife, Grace, and close family members are reported to be at his bedside.
The tyrant has undergone several bouts of therapy in Asia in recent years.
But his condition has now deteriorated and there were claims tonight that he has agreed to hand over power to his feared henchman and defence minister, Emmerson Mnangagwa.
Rumours over Mugabe’s health have been rife in recent weeks because of his frail appearance. There was heightened speculation today when the Zimbabwe government postponed a cabinet meeting at the last minute.
The Zimbabwe Mail, quoting a senior official of Mugabe’s ZANU-PF party, said the leader, who has ruled the country since its independence from Britain in 1980, was undergoing intensive treatment in Asia.
Mugabe was supposedly in Singapore to oversee his daughter Bona’s enrolment at university.
But registration does not start until September and opponents said it was unlikely he would travel abroad to deal with such a matter in person.
Sources in Iran, which has a warm relationship with Zimbabwe, said Mugabe had agreed on his successor.
The Tehran Times said the tyrant had entered into a ‘gentleman’s agreement’ to hand over power to 65-year-old Mnangagwa, who helped orchestrate the violent opposition to Britain in the 1970s.
The former Zimbabwe intelligence chief was also widely blamed for the brutality following the 2008 presidential election after Mugabe’s rival, Morgan Tsvangirai, took an early lead in the voting.
He is also thought to have played a major role in the crackdown of the opposition Zapu party in the 1980s that left thousands of civilians dead.
There was no comment on Mugabe’s health tonight from either his family or from the Zimbabwe government.Mugabe’s aides have denied there is a medical emergency, claiming he is enjoying an Easter break in Asia with his family.
But Zimbabwe’s vice president, Joice Mujuru, has reportedly cut short her trip to Asia to return home and prepare for the possibility of Mugabe’s death.
The tyrant is understood to have travelled to Singapore eight times last year for medical treatment. A diplomatic cable released last year by Wikileaks said Mugabe was diagnosed with prostate cancer in 2008 and given five years to live because it had spread.
He is said to have defied pleas from his own doctors to step down.
His ailing health has been cited as the main reason that a hard line faction of his ZANU-PF party has pushed to rush through new elections.
The Zimbabwe Mail quoted a British-based Zimbabwe analyst, who wished to remain anonymous, as saying: ‘Mugabe’s health impacts entirely on Zimbabwe’s political landscape. Everything revolves around his health and his age.’
In February, Mugabe declared himself ‘fit as a fiddle’. Last month he celebrated his 88th birthday with a lavish party in the capital, Harare, reputed to have cost £650,000.
The leader was said to have feasted on a cake in the shape of a crocodile.
Mugabe was hailed as a hero by many Africans when he came to power 32 years ago with Zimbabwe looked on as a model for a successful transition from white rule.
But the nation’s fortunes have plunged together with Mugabe’s reputation.
He is now regarded as one of the world’s worst human rights abusers. He has been accused of murdering thousands of his own citizens and brutally crushing all opposition to his rule.
His policies have also been blamed for driving Zimbabwe into bankruptcy.
Mugabe’s land reforms in particular, leading to violent seizures from white farmers, have been harshly criticised by the British and American governments.
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