NEW YORK, Feb 8 (Reuters) - The U.S. Treasury Department on Thursday sold $16 billion of 30-year government bonds at a yield of 3.121 percent, which was the highest yield at a 30-year auction in 11 months, Treasury data showed.

The ratio of bids to the amount of 30-year issue offered was 2.26, marking its weakest reading since November. This gauge of overall auction demand was 2.74 at the prior 30-year bond sale in January. (Reporting by Richard Leong; Editing by Andrew Hay)