Meanwhile, the US added its voice to growing criticism of last week's general election which the opposition described as a "fraud".

The US government said there was systemic bias against the opposition and highlighted credible reports that monitors were forced to alter some election result forms. The electoral commission rejected these claims.

A statement from South Africa's presidency said South Africa was conscious that the elections took place under a difficult economic environment because of sanctions against Zimbabwe.

It also acknowledged concerns from independent election observers about the legitimacy of the result.

Some monitors said the poll fell short of international standards and the requirements of Zimbabwe's own constitution.

South Africa, Russia and China are key trade partners of Zimbabwe, and their backing of the poll is significant as Zimbabwe is facing the prospect of further Western isolation and sanctions after criticism of the poll.

The opposition Citizens Coalition for Change is still tallying its own results before deciding on a concrete plan of what to do next. But the congratulatory messages to President Mnangagwa are perhaps a reflection that Zimbabwe's main allies are ready to move on and accept the results.