Rio Tinto has sacked two top executives after a probe into $10.5 million in payments linked to iron mining in Africa.

Rio was eager to point out that it made no suggestion that the officials or related consultants acted illegally, but the payments involving the two former Rio Tinto chief executives do not help the company, which has campaigned for transparency especially in projects like Guinea's $20 billion Simandou mine.

The world's second-largest miner terminated the contracts of Energy and Minerals Chief Executive Alan Davies and Legal and Regulatory Affairs Group executive Debra Valentine after an internal investigation into 2011 contractual arrangements.

The investigation was based on emails which showed then-CEO Tom Albanese, then-iron ore boss Sam Walsh, and Davies discussed a $10.5 million payment to Francois de Combret, a former investment banker operating in Guinea.

Rio's board found Davies, who ran the Simandou project at the time, and Valentine did not meet standards expected of them under its global code of conduct.

The company said in a statement that its decision did not pre-judge the course of any external inquiry into the matter.

Rio has alerted U.S., British and Australian regulators about the payments.

Davies is taking legal action.

“I have not been privy to Rio Tinto's internal investigation report, nor have I had any evidence of the reasons for my termination of my employment given,” he said.

“My rights are fully reserved, and I have been left with no option but to take the strongest possible legal action in response.”

Valentine had already stepped down, and is yet to make comment.

Rio Tinto is backing away from the entire project, announcing plans to sell its 46.6 percent stake in the Simandou project to the miner's Chinese partner, Chinalco

This move would be hindered by any potential regulatory investigation, though none has yet been announced.