The United States will put into circulation a newly designed $100 bill in October that aims to thwart counterfeiters with advanced security features, the Federal Reserve said on Wednesday.

The new greenbacks still bear the portrait of Benjamin Franklin, an 18th century luminary who helped found the new American republic.

The changes in design are mostly in anti-counterfeiting features such as a blue three-dimensional security ribbon and alternating images of bells and the number 100 that move and change as the viewing angle is tilted.

The new notes, which cost slightly more to produce, also feature a bell image inside a picture of an inkwell that changes from copper to green when tilted, as well as a large “100” that does the same.

Under prior plans, the bill was supposed to enter circulation in February 2011, but “its introduction was postponed following an unexpected production delay,” the Fed said in a statement.

The $100 note is the most frequently counterfeited denomination of U.S. currency outside the United States, due to its broad circulation overseas.

The billions of older-design $100s already in circulation will remain legal tender after the new notes are released.

In recent years, U.S. officials have been trying to combat the continued production of extremely high-quality counterfeit $100 notes they say are produced in North Korea, dubbed the “supernote,” which are undetectable to nearly all but the most sophisticated currency experts.

The U.S. Secret Service, the agency charged with policing the integrity of the nation’s currency, maintains that only a tiny fraction of a percent of currency in circulation is counterfeit. But Secret Service officials have said they still encounter supernotes and other highly sophisticated fakes from overseas.

The new notes have been in development since 2003. The blue security ribbon is woven into the note’s fabric – not printed on. Another security strip, visible to the left of Franklin’s head when the note is held up to light, is embedded into the fabric. Like the old note, the new one has a watermark of Franklin’s portrait, also visible when held up to light.

The old notes will be destroyed and replaced as they pass through the Fed system.

The U.S. dollar is the dominant currency used in international trade, and even serves as the primary currency in some countries. Officials have said as much as two-thirds of Federal Reserve notes in circulation are outside the United States.

The Fed said officials will be “reaching out to businesses and consumers around the world” to educate them on how to identify the new bill.

For more information on the new design for the $100 bill, please see www.newmoney.gov.

(Reuters)