Longer-dated U.S. Treasuries fell on Friday and pushed portions of the Treasury curve to record steep levels after Federal Reserve Chairman Ben Bernanke raised expectations the Fed would try to create inflation.

That made holding 30-year Treasury bonds, and even 10-year notes, at current low yields less attractive, since future inflation would drive interest rates higher and erode their value.

Longer-dated bond prices also continued to be undermined by a poor reception in an auction of 30-year securities on Thursday. Shorter-dated Treasury debt prices were supported by the Fed purchasing government securities on the open market.

Thirty-year Treasury bonds yielded 3.99%, up from 3.92% late on Thursday. The yield reached as high as 4.02%, the loftiest in five weeks, and the bond was on track for its biggest weekly rise in yield since August, 2009.

The rise in longer-dated rates also steepened the Treasury curve dramatically, with the spread between five-year note yields and 30-year bond yields, along with the spread between 10-year note yields and 30-year bond yields, moving to record wide levels, according to Thomson Reuters DataStream.

Traders sold long bonds and 10-year notes after Bernanke's speech, delivered to a conference in Boston, conveyed a focus on inflation targets.

Benchmark 10-year Treasury notes yielded 2.57%, up from 2.51% late on Thursday.

Separately, data on U.S. consumer prices showed a smaller-than-expected rise in September.

Fed action on inflation will most likely entail a new Treasury purchase program, something bond traders have been anticipating for weeks.

Trading in Treasury Inflation-Protected Securities also supported the idea that the sell-off was based on inflation expectations.

The spread between the yields on U.S. 10-year TIPS and regular 10-year Treasury notes reached 2.14%, its widest in nearly 5 months. On Aug 24, the spread, which is a market gauge of inflation expectations, was 1.50%.

Three-year notes yielded 0.60%, down from 0.62% late on Thursday.