The businessmen, who are from Leicester, the United States and Taiwan, were last night being questioned at Bishopsgate police station in the City of London.
The three were arrested at midday as they emerged from a bank in the City of London after depositing bonds with a face value of $800m. The police have seized the bonds, but do not yet know from where they originated.
The police operation, carried out in conjunction with the United States Secret Service, is believed to have curtailed what could have become a string of further frauds in the United Kingdom and abroad.
Detective Inspector Ken Stewart, of the City of London Police, said: "We have retrieved a substantial amount of fraudulent documents [the bonds] circulating in the City's financial markets. This was a concerted effort to defraud financial institutions. The documents could appear to be genuine to someone who was not a specialist in this field."
Further investigations are being undertaken but City police were yesterday unable to say whether further arrests would be made. They are also investigating whether the businessmen had approached any financial institutions other than the bank, which police declined to name, as part of the alleged fraud.
City police were aided by an agent of the US Secret Service, a department of the US Treasury which investigates violations of US Treasury rules. More than 40 officers of the City police were assigned to the investigation. Preparations for the operation have been carried out over the past 10 days.
A spokesman for the US Secret Service stressed that the bonds had no connection with the United States government or with American financial institutions.
The spokesman added: "These are totally fictitious instruments."
He said the criminals used sophisticated desktop publishing programs to mock up bonds that appeared to have been issued in the 1940s. He added that there were several similar cases every year in the US.
DI Stewart said police were checking to confirm that the bonds were fraudulent. He said they could be used to obtain smaller sums from investors who were unaware of their authenticity.
Because police were able to intercept the bonds before they entered London's financial system, the scale of the fraud had been reduced.
If the bonds had been lodged with the bank, other frauds could have followed, police said.
DI Stewart added: "This has been an extremely successful operation. It is an excellent example of the value of partnerships forged with law enforcement agencies around the world which assist in preventing international fraud."