"Mr Manyi left his position on the 25 August 2012 after serving his full three-year contract," the presidency said in a statement.

Manyi was CEO of the Government Communication and Information System (GCIS) and Cabinet spokesman.

He joined GCIS in February 2011 from the department of labour, where he was transferred to complete the rest of his contract as director general in the public service.

The presidency said Manyi had done sterling work in communicating Cabinet decisions and government policy.

"Mr Jimmy Manyi was very instrumental in communicating government programmes particularly the five priorities of government to the people of South Africa.

"He has made a good contribution to government communication and Cabinet communication processes," said Performance Monitoring and Evaluation Minister Collins Chabane.

"On behalf of the president, Cabinet and government I would like to thank Mr Manyi for his contribution to government communication."

Chabane has appointed Phumla Williams as acting CEO of GCIS until the position has been filled. Williams was the deputy chief executive officer of corporate services.

Manyi's position would be advertised and filled after a suitable candidate had been found, the presidency said.

On August 6, ANC Head of Monitoring and Evaluation Jessie Duarte issued a statement denying that she was replacing Manyi as head of GCIS.

"I want to state that such allegations are misleading to the public and they are not factual.

"I want to place it on record that any senior position available in government has to be advertised, interviews will follow and recommendations go to the Cabinet before one can be appointed to the position of Director General.

"I can confirm that the position has not been advertised yet and there is no one associated with the position," she said.