President Jacob Zuma's office says the president did not intervene with Equatorial Guinea to obtain the release of four South Africans held there.  Zuma is due to visit the West African country later today. 

Equatorial Guinea has announced a pardon for South African mercenary Nick du Toit, British coup plotter Simon Mann and three other South Africans. All were serving jail terms for their part in a failed coup in Equatorial Guinea in 2004.

Reports have named the other three South Africans as George Alerso, Sergio Cardos and Jose Sundays. 

Equatorial Guinea's information ministry said in a statement that President Teodoro Obiang Nguema had granted Mann a pardon on humanitarian grounds, a year after the British mercenary was sentenced to 34-years in prison for plotting to overthrow Nguema.

The information ministry referred to an upcoming visit by Zuma in the statement. "The orders were signed on the eve of the official visit by the president of South Africa, Jacob Zuma, to Equatorial Guinea," it said.

Zuma's spokesperson confirmed he was travelling to Africa's third-largest oil producer later today for a one-day visit, during which he would be meeting with Nguema.