After Chinese markets closed, China's central bank resumed its easing cycle, injecting an estimated $100 billion worth of long-term cash into the economy. Long-dated U.S. Treasury prices rose after the weak housing data supported the view that the Federal Reserve could slow the pace of interest rate hikes this year. Recent U.S. economic reports including a pick-up in inflation had shifted the view the Fed could raise interest rates before year-end.
The benchmark 10-year note US10YT=RR was last up 3/32 in price to yield 1.752 percent, down from 1.764 percent late on Friday.
Finance ministers and central bankers from the Group of 20 announced an agreement to use "all policy tools – monetary, fiscal and structural – individually and collectively" to reach the group's economic goals.
The dollar rose against a basket of six major rivals, pushing the dollar index up 0.2 percent. But the greenback tumbled against the Japanese yen, losing around 1 percent.
Gold, another investor "safe haven," rose and was on track for its best month in four years.
Crude futures rose as Saudi Arabia said it would work with other oil producers to limit oil market volatility.
Brent futures LCOc1 were trading at $35.98 a barrel, up 2 percent from their previous close. U.S. crude futures CLc1 were up 2.5 percent at $33.40.