Mugabe is 92 and Africa’s oldest ruler who has held power since the country gained independence from Britain in 1980.

READ: Zimbabwe’s Mugabe paves way for bond notes 

But he is increasingly looking frail, stoking a scramble in his ruling ZANU-PF party to succeed him.

One faction is widely believed to be manoeuvring to impose his wife Grace as a possible successor, another backs Vice President Emmerson Mnangagwa, who has the support of war veterans.

While the two sides have traded barbs for months, Tuesday’s comments by Jonathan Moyo, an outspoken higher education minister who is linked to the G40 group behind Grace, are the most overt attack on the man assumed to be her biggest rival.

Moyo, a senior ZANU-PF official, said in a public statement that Mnangagwa was illegally using the anti-graft commission to further his political career. Mnangagwa could not be reached for comment, and his aides said he was busy in meetings.

Moyo said the Zimbabwe Anti-Corruption Commission had on several occasions tried to arrest him on false graft charges at Mnangagwa’s behest.

He said this was part of a plan “intended to secure that the political ends currently being pursued by the vice president are advanced in relation to what has become public knowledge about the desire to secure a front foot in succession politics”.

The commission said last month it wanted to question Moyo on suspicion of abusing government funds, allegations the cabinet minister denies and says are a political plot against him.

The commission said it would study Moyo’s statement and respond appropriately when it was ready, without specifying when that would be.

Political analysts say Mugabe has manipulated Zimbabwean politics to set himself up as a president for life but fear the country could suffer instability if he dies in office before the matter of his successor is resolved. (Reporting by MacDonald Dzirutwe; Editing by Alison Williams)