Interest rates fell further on Monday, as economic fundamentals continued to bolster U.S. government bonds.

In late New York trading, the Treasury's 30-year bond yielded 6.31 %, down from 6.34%. Yields on 30-year bonds have fallen about 20 basis points in the last week.

"The economic data keep coming in slightly weaker than forecast, and there's no inflation," said Astrid Adolfson, economist for MCM Money-Watch, in explaining the drop in yields.

Interest rates also fell on the short end of the market. The Treasury auctioned a total of $24.6 billion in three- and six-month bills.

Three-month bills were sold at an average discounted rate of 3.03%, versus 3.05,% the week before. The six-month bills were sold at 3.12%, down from 3.18%.

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