Ousted dictator Robert Mugabe failed to resign during a television address last night and now looks set to face impeachment.
Mugabe has been pictured negotiating with the generals and even attended a graduation ceremony in Harare despite his fall from power.
But Grace has not been seen since the military takeover on Tuesday.
Former Foreign Secretary Malcolm Rifkind said: “There is a big question mark over his wife Grace Mugabe. There are reports she has been arrested so she may not be able to leave the country.”
The generals behind the military coup wanted to stop Grace from succeeding her 93-year-old husband when he dies.
Since the coup, Mugabe’s wife has been moved between detention facilities at military bases across Zimbabwe, a source told the Daily Mail.
“She was taken away both to prevent them colluding and conspiring, and to isolate her husband further,” one military official said.
“It’s best she is taken out of the picture and forgotten about for now – we will decide what to do with her later.”
But other sources told the Guardian she was in her husband’s Harare residence when he was detained on Tuesday and had not moved since.
Last week there were rumours that Grace had fled to Namibia. But the reports were later denied and she is thought to be in Zimbabwe.
Grace’s path to power was cleared when her rival, vice president Emmerson Mnangagwa, was fired two weeks ago.
But her short-lived triumph over Mnangagwa proved to be her ultimate downfall.
The military rose up against Mugabe in support of Mnangagwa and he has now replaced Mugabe as the leader of Zanu-PF.