The government said Monday it will need to check more than 1 billion new $100 bills because of production problems that have left unwanted creases in many of the notes.

Officials of the Bureau of Engraving and Printing said Monday that they are examining 1.1 billion of the new bills to determine how much of the currency will have to be destroyed.

Darlene Anderson, a spokeswoman for the bureau, said officials believe a large proportion of the new bills will pass inspection and be placed into circulation. The currency is being held in vaults at the bureau's two printing facilities, one in Washington and the other in Fort Worth, Texas.

The currency had originally been scheduled to go into circulation on Feb. 10. Anderson said a new date will not be set until the production problems are resolved.

The government had announced on Oct. 1 that the currency was being delayed but it had not given an estimate of how many bills might have been affected by the production problems.

"We are confident that a very high proportion of the notes will be fit for circulation," Anderson said.

She said that the bureau was working to develop a process to check all of the new notes that have been printed as well as determine the best approach to take to deal with the unwanted creasing in the new bills.

The bills have been redesigned with sophisticated elements aimed at thwarting counterfeiters. Those include a disappearing Liberty Bell in an inkwell and a bright blue security ribbon that is composed of thousands of tiny lenses.

Those lenses magnify the objects underneath them to make them appear to be moving in the opposite direction from the way the bill is being moved.

Anderson said that until the production problems are resolved, the bureau will continue to use the previous $100 bill design, which is considered to still be effective against counterfeiters.

"We will be able to meet demand for U.S. $100 notes," she said.

The redesigned $100 bill was unveiled by Treasury Secretary Timothy Geithner and Federal Reserve Chairman Ben Bernanke during ceremonies at the Treasury Department last April.

Benjamin Franklin will remain on the C-note, which is the highest value denomination in general circulation. It is also the most frequent target of counterfeiters.

The $100 bill is the last note to undergo an extensive redesign in an effort to thwart counterfeiters armed with ever-more sophisticated copying machines. The redesigns began in 2003 when the government added splashes of color to the $20 bill. That makeover was followed by redesigns for the $50, $10 and $5 bills. The $1 bill isn't getting a makeover.