Mr Mugabe ignored a midday deadline by the party's central committee to resign.

Update 7.09pm: Lawyers for the young model who claims Zimbabwe's first lady Grace Mugabe assaulted her in a Johannesburg hotel have said that her family has been approached with an offer of money to drop the allegation.

South African officials are debating whether to grant diplomatic immunity to Zimbabwe's first lady Grace Mugabe, who is accused of assaulting a 20-year-old model in Johannesburg this week.

Zimbabwe's first lady Grace Mugabe has requested diplomatic immunity over an allegation that she assaulted a young model in Johannesburg earlier this week, South African police said.

Zimbabwe's first lady Grace Mugabe has filed a $15m (€11.4m) lawsuit against a newspaper after it published a story citing WikiLeaks cables alleging her involvement in illegal diamond deals.