A distressed energy-trading company overstated its assets by more than $3bn using “routine and pervasive” forgery, while its founder oversaw years of disastrous bets on oil derivatives, a report filed with a Singapore court said.

The study by interim judicial managers, or court-appointed independent administrators, offers the first detailed account of the implosion of Hin Leong Trading, a closely held Singapore company that owes $3.5bn — mostly to banks, including HSBC Holdings.