Four executives from Mellitah Oil & Gas, a JV between Libya’s National Oil Company and Italian firm Eni, have been detained in Tripoli for alleged fraud over a $425mn floating storage and offloading vessel (FSO) commissioned in 2012.

The 1.5mn-barrel vessel was built by South Korean yard STX Offshore & Shipbuilding and began operating in February on the Bouri oil field, 120km offshore. It was delivered in May last year, some 11 months late.

The executives were detained by the...