Citibank, the world's second largest bank, has acknowledged that it and several other major New York banks have received formal requests for information from the Justice Department in connection with a federal investigation of possible collusion on the part of those banks in foreign currency trading.

On Thursday, the Justice Department confirmed it has issued "several CIDs (civil investigative demands)" in connection with its probe of possible manipulation of the price of the dollar around the world.

A Justice Department spokesman said the issuance of the CIDs is an indication the investigation has entered formal stages. Several other federal agencies, including the Securities and Exchange Commission and the Office of the Comptroller of the Currency, have announced the opening of related preliminary investigations.

The probes began after former Citibank empolye David Edwards filed suit against the bank, charging that he had been wrongfully dismissed merely because he raised allegations within the bank that it may have been breaking currency control and tax laws in several foreign countries.

A report subsequently done for the bank by its lawyers and accountants confirmed that some foreign laws may have been broken.

But before filing suit Edwards wrote a fictionalized account of a day's activity in a European trading room for a large U.S. bank.

The story implied it was possible for a handful of money traders to manipulate the price of the dollar for a short term by working in concert. Such a situation concerns economists who feel that a recent two-year slide of the value of the dollar may have been at least somewhat artificial, influenced by widespread currency speculation, not by economic conditions in the U.S.