Treasury Secretary Timothy Geithner says the U.S. government "will never" lose its sterling credit rating despite big budget deficits and a newly increased debt limit that now tops $14 trillion.

Geithner says in an interview broadcast Sunday that in times of economic crisis, international investors will continue to buy U.S. Treasury bonds because the bonds are a safe investment.

Moody's Investors Service recently issued a warning that the government's credit rating could eventually be in jeopardy if nation's finances don't improve.

The cost of borrowing would increase significantly if the ratings service lowered the credit rating, also known as a bond rating, for U.S. Treasuries.

Geithner tells ABC's "This Week" that will never happen.