Bonds extended earlier gains on Wednesday after the Federal Reserve signaled that it would remain patient when it comes raising interest rates.
In a statement after its latest policy meeting, the Fed made clear that no rate increase is imminent. Chair Janet Yellen said after last month's meeting that by saying it would be "patient," the Fed was signaling there would be no rate increase for at least two meetings.
The Fed's statement Wednesday said the factors holding inflation below its 2 percent target rate have intensified since its last meeting in December. Inflation has stayed ultra-low partly because of a plunge in energy prices and a steadily strengthening dollar.
Thirty-year bonds were last up 1 18/32 in price to yield 2.34 percent. Yields on the long bond have repeatedly set fresh lows this week and on Tuesday dipped to a record low of 2.328 percent, according to Thomson Reuters data.
Prices on benchmark 10-year Treasury notes were also up, with the yield at 1.76 percent on a price rise of 18/32. data. Shorter maturities were little changed.
The Treasury Department auctioned $26 billion in two-year notes at a high yield of 0.540 percent. The bid-to-cover ratio, an indicator of demand, was 3.74, better than the recent average of 3.36.
Trading was thin and choppy, with demand for long-dated bonds continuing to be fed by relatively fat U.S. yields and moderating expectations of inflation, analysts and traders said.