Willkie Farr & Gallagher, Simmons & Simmons, Pinsent Masons and Locke Lord have taken roles on civil and criminal claims stemming from the collapse of FTSE 250 oil company Afren, as the UK's Serious Fraud Office (SFO) announces charges against two of its executives.

The former chief executive of Afren, Osman Shahenshah, and the former chief operating officer Shahid Ullah both face four counts of fraud and use and possession of criminal property, in charges to be brought by the SFO tomorrow (27 September).

Simmons & Simmons is representing Shahenshah, who will appear at Westminster Magistrates' Court tomorrow.

Locke Lord is advising Ullah, who will also appear at Westminster Magistrates' Court tomorrow. Both stand accused over payments they received via secret companies they controlled relating to more than $400m of Nigeria business deals.

Simmons' team is being led by corporate crime partner Stephen Gentle, while disputes partner David Grant is leading for Locke Lord.

An SFO release said: "The alleged fraud is claimed to have led to the collapse of the $2.6bn oil giant by their administrators, who in related civil claims are seeking damages in excess of $500m from the defendants and a Nigerian associate."

The pair are also facing a separate $500m civil suit, brought by Afren's administrators AlixPartners, which claims that the alleged fraud led to the collapse of the $2.6bn business.

Willkie Farr & Gallagher is representing AlixPartners on the claim.

Court documents also name Nigerian oil field company Oriental Energy Resources as a defendant in the civil case, alongside its founder Alhaji Muhammadu Indimi, whose son is married to the daughter of Nigeria's president Muhammadu Buhari.

Pinsent Masons is acting for Oriental and Indimi on the case.

In 2014, Willkie Farr led an independent review into Afren, which found irregularities in its expense payments that led the oil company to report itself to the SFO.

The review alleged that evidence was identified in respect of the receipt of unauthorised payments amounting to $45m for the benefit of Ullah and Shahenshah, alongside some other employees and third parties, relating to the Ebok oilfield.