Clifford Chance has landed a role advising oil services company Unaoil, as it is investigated by the UK's Serious Fraud Office (SFO).

The SFO confirmed yesterday that it is "conducting a criminal investigation into the activities of Unaoil, its officers, its employees and its agents" over suspected offences of bribery, corruption and money laundering.

The magic circle firm has been appointed by the Monaco-based oil consultant – which offers companies local knowledge on workforce, engineering and construction issues – to advise it during the investigation. The firm's team is being led by London white collar and regulatory partners Luke Tolaini and Judith Seddon alongside investigations director Zoe Osborne.

The allegations against Unaoil first came to light in March following an investigation by Huffington Post and Australian broadsheet The Age, based on a cache of leaked documents.

The paper reported that between 2002 and 2012 Unaoil bribed officials to help its clients win contracts across the globe.

According to the reports, Unaoil paid bribes to local companies and state agencies to secure contracts for clients including Rolls-Royce, US giant Halliburton, Australia's Leighton Holdings and Korean companies Samsung and Hyundai.

The news outlets claimed Unaoil's activities spanned a wide selection of countries including Iraq, Kazakhstan, Iran and the United Arab Emirates.

It was also reported in March that the company's offices in Monaco were raided at the request of the SFO.

Unaoil has already instructed Kennedys to commence legal action against Fairfax Media, the owner of The Age, over the story.

Unaoil has previously turned to Jones Day for legal advice. The firm advised Unaoil in a dispute over an oil pipeline project in Iraq and the Northern Arabian Gulf, which the company subsequently won, being awarded $12.6m plus interest and costs in September 2014.

Jones Day head of projects and infrastructure Arman Galledari was listed as a non-executive director of Unaoil – having been made a director of Una Energy Group Holding in January 2014 – until his resignation in March 2016.

Galledari said he had not been contact by the SFO or any other regulatory body and was not under investigation.

Unaoil declined to comment on the SFO investigation but the company has previously denied the allegations, dismissing them as "unfounded". It said in a statement that the reports were "causing serious harm to our business, our employees and our reputation".

It added: "We take these extremely seriously and we will defend ourselves vigorously."