Washington, meanwhile, was delaying a decision on permitting some trade between US companies and China's telecom equipment maker Huawei, in retaliation for Beijing suspending its purchases of US farming goods, Bloomberg reported.
Worries about Italy, the euro zone's third-biggest economy, were rekindled late on Thursday after its deputy prime minister, Matteo Salvini, sought snap elections following a period of public fighting between Salvini's League party and the anti-establishment 5-Star Movement.
Adding to investors' jitters was news that the British economy unexpectedly contracted in the second quarter, the first time since 2012, as Prime Minister Boris Johnson prepares to pull the country out of the European Union in October.
"These are not positive news, but they are bond-friendly news," said Mary Ann Hurley, vice president of fixed income at D.A. Davidson in Seattle. "No one wants to go short going into the weekend because they don't know what's going to happen."
At 10:52 a.m. (1452 GMT), benchmark 10-year Treasury yields were 1.3 basis points lower at 1.702%. They hit 1.595% on Wednesday, which was their lowest level since October 2016.
Ten-year yields are on track for a second week of decline, which would be their steepest two-week drop in nearly eight years, according to Refinitiv data.
The yield on the 30-year, or long, bond was down 3.3 basis points at 2.214%. On Wednesday, the 30-year yield fell to 2.123%, within striking distance of an all-time low of 2.089% set in July 2016, according to Refinitiv data.
Longer-dated yields were also supported by data that showed US domestic producer prices grew modestly in July, with core prices posting their first decline since October 2015.
Sluggish inflation, together with trade and geopolitical turmoil, reinforced traders' expectations the Federal Reserve would lower its key lending rate by at least a quarter point at its Sept. 17-18 policy meeting.
Interest rates futures implied traders expect the US central bank may cut rates at each of its policy meetings the rest of the year, according to CME Group's FedWatch program.