UK and US regulators were told of a state-led drive to "rig" interest rates in the 2008 financial crisis, but covered it up, evidence indicates.
Documents suggest lenders sharply dropped their interest rate estimates after pressure from central banks.
Evidence was not shown to juries where bankers were jailed for smaller-scale interest rate "rigging".
Regulators said they had followed disclosure rules, declined to comment or in one case rebutted the claims.
