A lawyer for Libya’s sovereign wealth fund disclosed an internal email from a Goldman Sachs banker warning colleagues not to “milk Libya” by selling complicated trades that fund officials weren’t prepared to handle.

The internal email from Driss Ben-Brahim, who left Goldman in 2008, was cited in the High Court in London during closing arguments this week of a case in which the Libyan Investment Authority is suing Goldman for $1.2 billion to cover losses from derivatives it bought from the bank in 2008. The fund alleges that Goldman executives exerted "undue influence" over its officials, who didn't understand the trades.