More than a dozen Aegean Marine Petroleum Network employees — including members of senior management — orchestrated a half-billion dollar fraud scheme with an unnamed former affiliate as the primary beneficiary, the bunkering company has alleged.

Following the results of an audit carried out by independent legal counsel hired by the New York-listed bunkering giant, Aegean Marine said up to $300m of its assets were funneled to OilTank Engineering & Consulting after a 2010 deal to build an oil terminal in Fujairah.

Also, the company said some $200m in accounts receivable will be written off as uncollectible. Auditors said those transactions, with shell companies, were carried out to obscure misappropriations to OilTank.

Both OilTank and the shell companies are said to be controlled by the unnamed former affiliate, who allegedly threatened employees with economic retaliation and physical violence to perpetrate a scheme that included forged bank statements, contracts and other documents. The employees who directed the scheme have been terminated, Aegean Marine said.

"Although the company intends to pursue [potential redress] vigorously, there can be no assurance that it will be able to recover a material portion of the losses it has incurred," a statement from the company read.

The audit results come as controversy swirls around Aegean Marine and its relationship with founder Dimitris Melisanidis.

Melisanidis was bought out of Aegean in 2016. He stuck around the company as a consultant until earlier this year, when a $367m deal for Aegean to buy Melisanidis-owned HEC Europe was scuttled in March and an investigation into financial wrongdoing launched in June.

According to Aegean, auditors were stifled by the former affiliate's continued control over emails and other electronic data. They say an attempt was made to delete them via remote software and action from the Hellenic Data Privacy Authority has kept auditors from reviewing or using some of the data.

In midday trading, Aegean shares were down 2.13% to $0.92.