US Treasury Secretary Scott Bessent [Photo/Agencies]

The United States Treasury Department could tap its nearly $1 trillion cash account to help fund planned purchases of government bonds, two Treasury sources told US media.

The Treasury announced last week that it would double the maximum size of liquidity-support buybacks in the 10 — to 20-year and 20 — to 30-year sectors from $2 billion to at least $4 billion per operation, starting Sept 9 and continuing through Nov 4.

Treasury Secretary Scott Bessent told CNBC that the move was aimed at keeping markets focused on fundamentals rather than headlines during "a quiet period in a thin market". However, he did not specify how the purchases would be financed.

The two sources told CNBC that it was not formally known how much of the Treasury General Account could be used, or whether it would be used beyond purchases of off-the-run securities. But they said the account was "considered to be available".