The Serious Fraud Office (SFO) has dropped a 10-year probe into former FTSE 100 miner ENRC, saying it does not have enough evidence to prosecute.

Prosecutors had been looking into the suspected payment of bribes by the company and people linked to it in the Democratic Republic of the Congo between 2009 and 2012.

But on Thursday the SFO updated its website to say the case is closed.

“Following our latest review of the investigation, we concluded that we have insufficient admissible evidence to prosecute, and closed the case,” it said.

“We would like to sincerely thank everyone who has co-operated with our investigation.”

SFO investigators also dropped three other probes, including one into suspected corruption by Rio Tinto in the Republic of Guinea.

In closing the Rio Tinto investigation, the SFO said it “is not in the public interest to proceed with a prosecution in the UK”.

But it said Australian police are still investigating the matter and it will support that probe.

The SFO in 2013 opened its investigation into the ENRC (Eurasian Natural Resources Corporation), a London-headquartered Kazakh mining firm set up in the early 1990s after the fall of the Soviet Union.

The company had been dogged by boardroom spats and allegations of wrongdoing for several years. It was taken private and delisted from London’s stock exchange in 2013.

The SFO’s investigation has not led to a prosecution of ENRC, but ENRC has launched a lawsuit over the case, seeking damages from the authority.

Last May, a court ruled that the agency breached its duties by accepting information from a lawyer hired by ENRC to run an internal investigation.

The judge cleared the SFO of other allegations.

A spokesperson for ENRC said: “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.”

Rio Tinto have been contacted for comment.