The fraud squad's year-and-a-half long investigation into Soma Oil & Gas cost the company £4.5m, City A.M. has learned.
The Serious Fraud Office (SFO) opened an investigation into Soma in July 2015 following allegations of bribery and corruption before closing it in December last year.
The UK company, which is chaired by former Tory leader Lord Howard, shelled out £1.1m in third party costs, such as legal fees as well as the costs the firms was ordered to pay when it unsuccessfully took the fraud watchdog to court in a bid to put the investigation to bed.
The remaining £3.4m relates to costs incurred because the company was forced to suspend its business plan for the probe's duration, and includes roughly £1.6m worth of manhours which the company's staff spent working on the investigation.
Although the figures are not a perfect comparisons, City A.M. revealed over the weekend that the investigation had cost the SFO just £59,912, not including permanent staffing costs, from start to finish.
"The SFO has concluded, based on the information and material we have obtained, that there is insufficient evidence to provide a realistic prospect of conviction," the fraud watchdog said when it announced it was closing the probe, although it added there had been "reasonable grounds" to suspect wrongdoing.
At the time the case was closed, Soma said it welcomed the end of the investigation and "looks forward to executing its plan to further explore what is believed to be very considerable hydrocarbon potential offshore Somalia in 2017 and beyond".
Both the SFO and Soma Oil declined to comment on the costs of the investigation.