South African President Jacob Zuma has told his Zimbabwe envoy to stop making public comments, after she was criticised by Robert Mugabe.

Mr Zuma, the chief mediator in Zimbabwe’s 2008-9 political crisis, said only he was authorised to comment ahead of the 31 July elections.

His envoy, Lindiwe Zulu, said last week that electoral preparations were “not looking good”.

Zimbabwe’s president then asked Mr Zuma to stop “this woman” from commenting.

President Mugabe is seeking to extend his 33-year rule and will face Prime Minister Morgan Tsvangirai at the ballot box.

The two long-time rivals have been sharing power since 2009, under a deal brokered by Mr Zuma.

A statement from Mr Zuma’s office said that some of the comments made about Zimbabwe had been unauthorised, unfortunate and inaccurate.

The statement did not refer to Ms Zulu by name.

She has previously said the elections should be postponed from 31 July, prompting Mr Mugabe to call her “stupid and idiotic”.

Two days of early voting for members of Zimbabwe’s security forces last week saw many logistical problems, such as a lack of ballot papers, raising fears that the election will not go smoothly.

After Ms Zulu’s comments last week, Mr Mugabe said:

“That persistent negative voice from South Africa… could it please be stopped?” the state-owned Herald newspaper reports.

“I appeal to President Zuma to stop this woman of theirs from speaking on Zimbabwe. We were given one facilitator with one mouth and that is President Zuma himself; that’s the voice, the only voice we want to hear.”

The election is the first to be held since a new constitution was approved in a referendum in March.

However, some of Mr Tsvangirai’s long-standing demands such as reform of the state media and security forces, seen as supporting Mr Mugabe, have not yet been implemented.

Last week, a South Africa-based satellite TV station aimed at Zimbabwe, 1st TV, was launched, prompting strong protests from Mr Mugabe’s allies