Johannesburg - The international relations department on Sunday said it was helping a South African man imprisoned in Equatorial Guinea.
"We are aware of the case and are rendering consular assistance to him and his family," spokesperson Clayson Monyela said.
The Sunday Times reported that Daniel Janse Van Rensburg, 49, had not been allowed to leave the country and had been in and out of the Black Beach prison since a business deal went sour last year.
Monyela confirmed Van Rensburg was in prison.
"There is a process underway," he said.
Van Rensburg apparently had a dispute with Equatorial Guinea businessman, Gabriel Bela Angabi, over a R30m aviation contract. He was arrested when he flew to Malabo last year to resolve the matter.
The newspaper reported that Angabi wanted R1m from Van Rensburg.
Van Rensburg's family told the Sunday Times they had not heard from him since a letter was sent to his South African business partner on 3 July. In the letter Van Rensburg said he had contracted malaria and typhoid in prison.
Meanwhile, Victor Manuel Ela Ela, a secretary at Equatorial Guinea's embassy in Pretoria, said Van Rensburg would be allowed to leave the country once he had resolved the matter.
"If he is not in South Africa by now it is because he has systematically failed to keep his word."