Former Zimbabwean first lady Grace Mugabe supported her ageing husband's "decision to resign", Robert Mugabe's former spokesperson George Charamba reportedly revealed.

Reports indicated that Grace had previously held her own presidential ambitions, as she reportedly led a campaign to get the then vice president Emmerson Mnangagwa out.

She was a key figure of the G40 faction that, until November 15, had the upper hand within the ruling Zanu-PF party.

Grace reportedly looked certain to become one of the country’s two vice presidents following the sacking on November 6 of then vice president Mnangagwa, who led a rival faction.

But, according to Charamba, Grace was behind her husband's decision to resign after the military took over control in November, reported Daily News on Sunday.

"Even the first lady (Grace Mugabe) was behind Mugabe's decision to resign," Charamba was quoted as saying.

Charamba said that Mugabe himself had wanted to leave office in his own terms but "they were a number of scenarios at play including marchers coming to force the veteran leader out of power", said Charamba.

He said that the last days of Mugabe’s presidency were very painful as loyalties to the nonagenarian had shifted.

Charamba said he had to remind the 93-year-old that there were "other dimensions" threatening his hold on power, including the peaceful protests that saw tens of thousands of Zimbabweans pour out onto the streets of Harare in support of the army.

"I said shefu (leader), you are concentrating on one dimension; there are others which are there which indicated harm to your well-being," Charamba quotes himself as telling Mugabe.

Eventually Mugabe handed in his resignation on November 21. This put a stop to the impeachment process, and triggered street celebrations that went on through the night.

Mugabe has since been assured of his safety by the new government of Mnangagwa and awarded a generous retirement package.