The United States voiced optimism Sunday that Argentina will be able to settle its long debt battle with "holdout" creditors, following a landmark offer from Buenos Aires.

Argentina's new government offered $6.5 billion Friday to settle the dispute and US court case that have roiled global sovereign debt markets while harming Argentina's ability to access international capital to fund its economy.

US Treasury Secretary Jacob Lew spoke by telephone Sunday with Argentine Finance Minister Alfonso Prat-Gay, to express American support.

"Lew commended Argentina's good faith efforts to resolve this longstanding dispute," a Treasury Department spokeswoman said.

"Secretary Lew echoed (court-appointed mediator Daniel) Pollack's strong hope that all creditors will be able to resolve their differences and reach agreements in principle with Argentina."

The holdouts, whose decade-long court battle against Buenos Aires was led by two New York hedge funds, are a minority class of creditors that refused to go along with the restructuring of the country's debt after it defaulted on about $100 billion in 2001.

Buenos Aires said it was offering the creditors roughly 75 percent of what they were claiming, covering the face value and accumulated interest on the bonds.