Addressing the party's annual conference, Mr Mnangagwa said Zanu-PF should always compete in elections which are credible, free and fair.

It's the first party congress since Robert Mugabe stepped down after 37 years in power, and delegates are expected to endorse Mr Mnangagwa as their leader and candidate for next year's pesidential poll.

They are also likely to confirm a lifetime ban from Zanu-PF on the former president's wife, Grace Mugabe.