NEW YORK: US Treasury yields fell slightly on Thursday in choppy trading after the European Central Bank lowered key interest rates and expanded its bond purchase program in a bid to support the euro zone's fragile economy.

The ECB surprised investors with an unexpected cut of its main refinancing rate to zero from 0.05 percent.

As expected, it lowered its deposit rate to -0.4 percent and raised its monthly bond purchases to 80 billion euros.

The benchmark 10-year Treasury yield was last at 1.887 percent, down slightly from late on Wednesday, while the 30-year bond yield slipped nearly 1 basis point to 2.674 percent.

Copyright Reuters, 2016