The fraud watchdog has told firms they will need to go "above and beyond what the law requires" if they want to co-operate with its investigations.
Guidance of corporate co-operation released by the Serious Fraud Office (SFO) states that firms need to be willing to identify any individuals suspected of wrongdoing "regardless of their seniority or position", and preserve hard copy evidence to pass on to the authorities.
SFO chief Lisa Osofsky, a former FBI lawyer, has already warned firms that it was not enough for a company to "call in a team of lawyers", only for them to cover incriminating material with legal privilege, a device that protects information from being disclosed without the permission of a client.
Any firms wishing to enter into a Deferred Prosecution Agreement – which allows firms to avoid full trial if they pay a penalty – need to be prepared to waiver privilege.
The SFO has entered into high-profile DPAs with Tesco, Rolls-Royce and Standard Bank.
However, in the guidance, released today, the SFO warned that even "full, robust co-operation" does "not guarantee any particular outcome".
Ben Morgan, a partner at the magic circle law firm Freshfields, said the SFO's guidance spoke to Osofsky's desire to speed up cases that were taking too long to prosecute.
He said the guidance asks not just for evidence to be handed over, but that financial statements are explained to it to help it process cases more swiftly.
"While there will be some businesses that will not want to co-operate with the SFO, it does have a customer base of companies that do want options in how they control their corporate criminal risk," he said.
"This gives companies a clear understanding of what they need to do."