Ten-year Treasuries held steady in price to yield 1.572 percent in Asian trade, staying above a one-month low of 1.542 percent hit on Tuesday.
The 10-year yield has declined since a speech by Federal Reserve Chairman Ben Bernanke last Friday prompted traders to increase bets that the US central bank will launch a new bond buying programme when it meets next week.
Volumes in Asia on Wednesday were very light, but Thursday's ECB meeting could trigger swings in safe haven Treasuries, said a trader for a US brokerage house in Tokyo.
"If it (the ECB) unveils something that is broadly in line with market expectations, we could see a risk-on type of move that pushes yields on Treasuries and German Bunds higher," the trader said.
"The ECB tends to be a wild card and I would expect to see some price action this time as well," he added.
Buttressing hopes that the ECB would soon unveil details of a new bond buying scheme aimed at reducing borrowing costs in peripheral euro zone countries such as Spain, ECB President Mario Draghi told European lawmakers on Monday that purchases of short-term sovereign bonds by the ECB would not breach European Union rules.