The mining company at the centre of a row over professional privilege has called for an independent inquiry into the Serious Fraud Office (SFO), accusing the office of failing to investigate a whistleblower’s letter.

The Eurasian Natural Resources Company (ENRC) said the SFO has admitted that it received, but failed to properly investigate, allegations it was sent six years ago.

ENRC has also filed an application at the High Court seeking pre-action disclosure from the SFO for a ‘number of claims including misfeasance in public office’. The High Court application seeks disclosure of, among other things, the notebooks of the SFO’s former chief investigator and accuses the office of a breach of contract and fiduciary duties.

An SFO spokesperson said: ’We see no merit in the application issued by the ENRC. Before they made this application for a narrow range of additional information, we told ENRC that we will be able to provide it if it exists. We remain satisfied that the issue was handled appropriately.’

ENRC is engaged in a long running battle with the SFO surrounding corruption allegations. It denies wrongdoing.

The letter in question, from July 2012, raised concerns about an allegedly unhealthy relationship between the SFO and Neil Gerrard, partner at international firm Dechert. It also included information about the alleged ‘leaking of confidential information’  by senior SFO officers. At the time Dechert was advising ENRC.

ENRC has also filed a separate negligence claim against Dechert, which alleged that Gerrard had leaked information to a US-based reporter for the Sunday Times. Dechert vigorously denies negligence, describing those claims as ‘unfounded’.

According to ENRC, its current solicitors, Hogan Lovells, have filed a freedom of information request with the SFO, asking for details of steps that the office took to investigate the allegations raised in the 2012 letter.

According to ENRC, the SFO’s response, in March last year, stated that its investigation consisted of no more than a ‘senior member of staff’ speaking to the ‘person believed to be the subject of the allegation’. There was no record of the investigation and no record of what policy or procedure was followed. ‘It appears that the SFO did not follow its own complaints procedure, which, at the time, specified that, if a complaint was of a “more serious nature (for example if criminality is alleged)” the director will appoint an independent reviewer (external to the SFO)’, ENRC said.

An ENRC spokesperson said: ‘This new evidence raises serious concerns about the SFO, the unethical behaviour of senior members of staff, and the procedures it did – or did not – follow. We have tried to meet with the SFO to discuss these claims but have so far have been refused. We hope this disclosure will force the SFO to answer these important questions.’

A spokesperson for Dechert said: ‘We stand by the work we did and look forward to the opportunity of defending it in open court. We note that the criminal investigation by the SFO into ENRC is continuing and deplore ENRC’s attempt to discredit that investigation by seeking now to publicise unwarranted allegations against Dechert and its personnel.

‘We emphatically reject any suggestion of an improper relationship between Dechert/Neil Gerrard and the SFO or that there was any unauthorised disclosure of information to or from the SFO. The work we did during our investigation was with the authority of, and with the knowledge of, those who were instructing us at the time. Attempts by a number of senior executives within ENRC to frustrate the investigation added to the cost and caused significant delays. We shall in the ensuing court proceedings fully address these unfounded allegations.’

The ENRC is engaged in an ongoing privilege dispute with the SFO which is heading to the Court of Appeal next month. This follows a high profile High Court ruling last year which determined that ENRC documents prepared for its own internal investigation were not protected by privilege.

If the appeal, listed for 3-5 July, goes the same way as the previous ruling, businesses would potentially have to hand over to prosecutors internal documents relating to criminal investigations.

The Law Society is intervening into the dispute on the issues related to legal professional privilege.