Zimbabwean Higher Education Minister Jonathan Moyo has reportedly claimed that Vice President Emmerson Mnangagwa threatened to kill him after he exposed his plot to topple President Robert Mugabe.

According to the privately-owned Standard, Moyo alleged that Mnangagwa made the threats following a politburo meeting last month in which Moyo accused the vice president of harbouring presidential ambitions.

The minister last month stunned the Zanu-PF politburo when he accused the veteran politician of capturing state institutions and working with ruling party renegades in the alleged plot to oust Mugabe.

In a letter to the ruling Zanu-PF Secretary for Administration Ignatius Chombo, Moyo wrote: "After my presentation, Cde Mnangagwa made a shocking statement to the effect that while he was in Mozambique, during the liberation struggle, people who made interventions such as my presentation to the politburo on  July 19 would have 'their head separated from their shoulders.".

Moyo said that he understood Mnangagwa's statement to mean he was threatening him with murder.

This came amid reports that Mnangagwa last week offered to resign over what he called repeated "public humiliation" by Mugabe's wife Grace.

According to sources, Mnangagwa believed there was a plot against him by the system to kick him out.

Grace had previously told the country's two vice presidents - Mnangangwa and Phelekezela Mphoko -  at a campaign rally in Chinhoyi that they were serving at her husband's will.

Grace warned the two deputies that they risked losing their jobs if they did not perform to the expectations of her husband.

A few days earlier, the First lady had publicly urged her ageing husband to name his successor.