The US Department of Justice is seeking an average of $1 billion each from the five global banks being investigated for alleged manipulation of currency markets, aiming to reach a simultaneous settlement.
Two of the banks are British, Barclays and Royal Bank of Scotland. The others are Citigroup, JPMorgan Chase and UBS.
Neither Barclays nor RBS would comment last night on a report that the justice department had set the $1 billion figure as the starting point in discussions over an eventual settlement.
Five banks agreed to pay a total of $4.3 billion to US regulators in November.
Reports suggest that the $1 billion is an average figure, with some being asked to pay more and some less.
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One unnamed bank that has co-operated from the beginning of the inquiry is said to be facing a much smaller sum.
Any settlement would resolve accusations of criminal activity on the part of the five. The banks involved have all set aside substantial sums to cover the costs of any eventual settlement with the US authorities.
Last week Barclays, announcing its results for 2014, reserved an extra £750 million, bringing the total put aside to £1.25 billion.
The bank has said that it is seeking a co-ordinated global settlement with a number of regulators.
A spokesman for the Department of Justice declined to comment last night.