oil rig
Unaoil is at the centre of a bribery scandal thought to involve companies across the world.iStock

The headquarters of Monaco-based oil firm Unaoil were raided on Thursday (31 March) by the local authorities following a British-led investigation into a corruption scandal involving businesses across the world.

In a statement released late on Thursday (31 March), the principality's government revealed authorities had acted following a request for help from Britain's Serious Fraud Office (SFO) and confirmed the inquiry focused on Unaoil.

Officials in Monaco added they had spoken with the company's executives over the course of the week, indicated the findings of the investigation could have serious implications for a host of other firms.

"These searches and interviews were carried out in the presence of British officials as part of a vast, international corruption scandal implicating numerous foreign oil industry firms," the Monacan government said in a statement. "The information collected is going to be examined by the British authorities as part of their investigation."

A spokesperson for the SFO said the fraud office was "aware of the allegations but can neither confirm nor deny our interest in the matter."

Unaoil, which was found in 1991 and is run by the Alshani family, a prominent Monaco-based business family of Iranian origin, was accused of "systematically corrupting the global oil industry" by the Huffington Post and Australia's Fairfax Media earlier this week.

In a report published on 30 March, both news organisations suggested the Monacan company had provided bribes worth billions of dollars to "carve up portions of the Middle East oil industry for the benefit of Western companies".

Fairfax, which described the six-month investigation as "the biggest leak of confidential files in the history of the oil industry," said it gathered information after analysing hundreds of thousands of internal emails that were leaked between 2002 and 2012.

According to the investigation, the firms involved in the scandal include the likes of Rolls-Royce, US giant Halliburton, Australia's Leighton Holdings and Korean icons Samsung and Hyundai. Two Iraqi oil ministers as well as senior officials from Libya, Iran and the United Arab Emirates are also implicated in the exchange of emails

When asked by Fairfax and the Huffington Post whether Unaoil had taken bribes, Ata Ahsani, the company's chief executive, was quoted as saying: "The answer is absolutely no."