Four South Koreans have been booked for investigation on charges of attempting to swindle money from local investors with a false pledge to return high profits if they invest in fake U.S. Treasury bonds, police here said Tuesday.

The four, including a suspect only identified by his surname Hong, allegedly tried to defraud the investors by falsely saying they would receive revenue in return for investing in $100 million bonds from the 1930's, according to Seoul's Seongdong Police Station.

The officers said they have seized a bag containing a total of 247 fake bonds and other fraudulent notes issued by the Federal Reserve Bank.

"We have received response from the U.S. government that such Treasury bonds have never been issued," said a police officer investigating the case.

The suspects all have previous criminal records in counterfeiting or forging official documents, according to the officers. (Yonhap)