During a plea and case management hearing of three individuals at Southwark Crown Court, the court heard that 22 other individuals have been written to by the SFO to say their alleged part in the Libor-rigging probe remains under investigation.
According to the SFO, none have been charged and some are yet to be interviewed.
A former UBS trader and two ex-brokers accused of being involved in a plot to manipulate Yen Libor rates appeared in Southwark Crown Court on Monday 21 October.
Terry Farr, 42, and James Gilmour, 48, both former employees of UK interbroker dealer RP Martin have been charged with conspiracy to defraud alongside ex-Citi and UBS banker, Tom Hayes, 34.
Mr Hayes faces eight counts of conspiracy to defraud while Mr Farr is charged with two counts and Mr Gilmour, one.
The maximum sentence for each count is 10 years. Mr Farr and Mr Gilmour, both of Essex, and Mr Hayes, of Surrey, are yet to enter pleas.