(Bloomberg) -- The UK’s Serious Fraud Office quietly dropped two long-running investigations into mining firms Rio Tinto Plc and Eurasian Natural Resources Corp., in another setback for an agency that’s expended years prosecuting suspected corruption across the commodities industry.

The SFO said Thursday it had closed its 2017 Rio Tinto investigation into allegations of corruption in Guinea after an internal review found it was not in the public interest to continue, according to an update on its website. No charges against individuals had been made.

Separately, the agency also announced it had closed a decade-long criminal investigation into ENRC citing “insufficient admissible evidence to prosecute.” The probe, one of the prosecutor’s longest, has been mired in controversy and allegations of reckless investigations against the SFO. It had focused on suspected bribe payments to secure mining contracts in the Democratic Republic of Congo between 2009 and 2012. 

The SFO, which both prosecutes and investigates the most serious white-collar crime in Britain, has a long list of recent missteps in the last few years. It has been accused of botching investigations, seen trials collapse, and a government-requested review that found the SFO’s failure in its Unaoil bribery case were caused by “cultural issues” in the agency.

Rio Tinto said in a statement after the announcement that it is “committed to conducting business to the highest standards of integrity.” The Australian Federal Police’s investigation into the case remains ongoing.

Since the SFO began its criminal investigation into ENRC, the Kazakhstan mining firm has initiated at least 16 legal proceedings in the US and UK against lawyers, investigators, contractors, journalists, a former SFO official and the SFO itself, according to anti-graft campaigner Spotlight on Corruption. 

“ENRC is pleased that the SFO has finally closed its investigation and that the SFO is taking no further action in respect of this matter,” a spokesperson said. 

(Updates with ENRC comment in the final paragraph)

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