The South African government will send a delegation to Equatorial Guinea to ensure a fair trial for the suspected mercenaries who allegedly plotted to overthrow the government there.
And it will appeal against any death sentence imposed on its citizens.
Foreign Affairs Minister Nkosazana Dlamini-Zuma said these decisions were made during lengthy talks on Wednesday afternoon between President Thabo Mbeki and his Equatorial Guinea counterpart, Teodoro Obiang Nguema M'Basogo.
"We said right from the beginning that we would like to help them to make sure that the trial is a proper, fair trial and that all the requirements of a fair trial are met," Dlamini-Zuma said.
"We will then continue to try and support them to make sure that there is indeed a fair trial."
A source close to the talks said the South African delegation would be part of a broader international collective, including the United Nations and nongovernmental organisations, which Nguema's government would invite to observe the trial.
"If you are there you can see whether the trial is fair or not ... they will sit there and listen and report back to our government," the source said.
Dlamini-Zuma said Nguema had also assured Mbeki that his government was trying to keep the prisoners "in as good a condition as possible".
"A fair trial also means that (the prisoners) are in some kind of reasonable condition, within the laws of that country."
On whether Mbeki and Nguema had discussed South Africa's opposition to the death penalty being imposed on its citizens, Dlamini-Zuma said: "Our approach is that the trial should go on and, depending on the outcome, we will then then take the necessary steps of appealing or whatever.
"We can't pre-empt the outcome of the trial, but when we come to that point, yes, we will engage the government around that issue should it be necessary."
The South African delegation would leave "soon", possibly within a month, and would probably consist of officials from the departments of justice, foreign affairs, safety and security and correctional services, she said.
The government did not want the trial to drag on forever.
The two presidents, accompanied by their foreign ministers, had not discussed any possible extradition to Equatorial Guinea of the 69 South Africans being held in Zimbabwe on charges related to the alleged coup.
Fifteen suspected mercenaries are being held in Equatorial Guinea's capital, Malabo, on charges of being involved in the plot. Eight of them hold South African passports.
Another 70 men - 69 South Africans and a British citizen - are being held outside the Zimbabwean capital, Harare, and face charges related to the alleged plot to overthrow Nguema.
They were arrested in early March at Harare International airport.
They had flown there from Lanseria, Johannesburg, in a private plane.
The families of those being held in Zimbabwe lost a High Court attempt to force Mbeki's government to have the men extradited to South Africa. An appeal will be heard by the Constitutional Court on Monday.
The men are due to go on trial in Harare next Wednesday.