South Africa's state oil company PetroSA said on Oct. 30 it had terminated its chief executive officer's contract, after placing her on special leave alongside two other executives to allow an investigation into their performance.

PetroSA said in a statement that it had reached an agreement with Nosizwe Nokwe-Macamo, but the terms were confidential.

"I am not in a position to say anything beside what is stated in the press release," spokesman Thabo Mabaso said.

The investigation on the three executives was triggered by declining revenues at the firm, which operates the world's third-largest gas-to-liquid refinery at Mossel Bay.

The firm had failed in its bid to enter the fuel retail market, and also reported a loss of 1.2 billion rand ($87 million) in its 2013/14 financial year.

The firm, which sells petrochemical products to South Africa's major oil companies and also exports to international markets, has previously said it would reduce its workforce by about 40 percent to cut costs.

($1 = 13.8170 rand)