(Adds details on investigations, ASIC comment) Australia's...

(Adds details on investigations, ASIC comment)

Australia's securities watchdog has closed its investigation into former Rio Tinto Ltd (RIO) executive Alan Davies over an alleged $10.5 million payment to a consultant in Guinea, citing insufficient evidence, according to a letter reviewed by Reuters.

Davies, formerly Rio's Energy and Minerals chief executive, was terminated in late 2016 after Rio Tinto became aware of emails https://www.reuters.com/article/us-rio-tinto-guinea-terminates-idUSKBN13B2Y4 from 2011 that referred to payments to the consultant in connection with its vast Simandou iron ore project in the West African nation.

According to the letter, ASIC's investigation covered directors duties like care and diligence and operating in good faith, obligations of honesty, and true and correct books and records.

"ASIC has concluded its investigation on the basis that there is insufficient evidence to establish to a court that there has been a breach of the law," the Australian Securities and Investments Commission (ASIC) said in a Oct. 19 letter addressed to Davies.

Davies, who said at the time there were no grounds for his termination, had no immediate comment. Rio Tinto did not have an immediate comment.

ASIC acknowledged the letter, saying it would not take enforcement action. "We've noted that ASIC may recommence its investigation, or commence enforcement action, if circumstances change," a spokesperson said.

London's Serious Fraud Office https://www.reuters.com/article/uk-britain-sfo-rio-tinto-idUKKBN1A9246 said in 2017 it was investigating the matter. Rio said at the time it had also referred the allegations to U.S. regulators.