Barclays has so far paid £194m to settle a US-led probe into payments made to countries or people on a sanctions list.
Barclays has been conducting an internal review into the payments and is reporting its findings to US government investigators.
The disclosure was buried deep in the bank's 126-page report on its interim results out today.
Authorities including the U.S. Department of Justice, the Manhattan District Attorney's Office and the Office of Foreign Assets Control are involved "in relation to the possible resolution of this matter," the bank said in its report.
Barclays says it is "in advanced discussions with these and other authorities" to end the probes.
In February, the bank said it is also being investigated by the FSA over payments involving people or countries under Treasury sanctions.
The bank disclosed the Department of Justice probe in 2007.
Barclays declined to comment.
Today the bank posted profits of £3.95bn for the first half of 2010, up 44% on the same period last year.
The bulk of the profits were provided by the group's investment banking arm, Barclays Capital, which made £3.4bn.
Earlier this week, RBS was fined £5.6m by the FSA for failing to check over a year period whether its clients appeared on a Treasury sanctions list.
Its results are due out tomorrow.
The FSA has said finance firms need to make sure they have systems and controls in place to prevent breaching sanctions and to comply with money-laundering regulations.
In 2007, the Treasury created an asset-freezing unit to maintain a list of firms under financial sanctions, enforced by the FSA.
Lloyds Banking Group paid over $350m in January 2009 to settle a U.S. investigation over processing payments which allowed Iran and other nations under sanctions to get access to U.S. financial markets.
Lloyds admitted to altering wire transfer information to hide the identity of its clients and allowing several billion dollars to go through U.S. banks in violation of the sanctions, according to the settlement with the New York District Attorney's Office and the Justice Department.
Robert Morgenthau, the Manhattan District Attorney at the time of the Lloyds settlement, said nine other major foreign banks had used the same technique to disguise illegal transfers.
