The military has said Mugabe is “safe and sound” in custody amid reports that his powerful wife has left Zimbabwe for Namibia in the wake of the coup.
It is not clear whether Mugabe will be deposed but the main goal of the generals appears to be stopping his wife Grace from succeeding him.
Grace was being lined up to take over from her 93-year-old husband after the vice president Emmerson Mnangagwa was fired and fled in exile last week.
Mnangagwa, who is known is the Crocodile, was Mugabe’s staunch ally for decades and used to be seen as his presumed successor.
The feared political figure is one of Mugabe’s former guerrilla comrades from the 1970s independence struggle.
Mnangagwa has long been seen a bridge between Mugbabe’s governing party Zanu-PF and Zimbabwe’s military operatives.
After a dangerous struggle before independence in 1980, Mnangagwa joined Mugabe in exile in Mozambique as his special assistant
There is mounting speculation that Mnangagwa will now take control of Zimbabwe, either officially or behind the scenes.
A Twitter account in Mnangagwa’s name said: “I’m back in the Country & will be quite busy over the next few days… Thank you all for the support & solidarity.”
Jane Morley, Zimbabwe analyst at the Economist Intelligence Unit, suggested that Mugabe could be forced to resign, paving the way for elections.
She said: “A managed election process would in all likelihood lead to the victory of former vice-president Emmerson Mnangagwa, the army’s favoured candidate.”
She added: “Even if the military returns to barracks (as it has pledged to do), and elections lead to a Mnangagwa presidency, the army will still have played a key role in determining who leads the country.”
Professor David Moore, speaking from Zimbabwe, said he did not believe Mugabe will be deposed. He told Al Jazeera: “It’s an inside-the-party coup. The president has not been deposed.”