Washington, Aug 3 (IANS): US Treasury Secretary Janet Yellen has again urged Congress to raise the debt limit as soon as possible after the federal borrowing cap was reinstated after a two-year suspension.

"I respectfully urge Congress to protect the full faith and credit of the US by acting as soon as possible," Yellen said in a letter to congressional leaders sent on Monday.

Yellen also said that the Treasury Department on Monday began using "extraordinary measures" to prevent the US from defaulting, including a debt-issuance suspension period lasting through September 30 and suspending investments in retirement funds for civil servants and postal workers.

She previously warned that the Treasury could exhaust those extraordinary measures soon after lawmakers return to Washington from their summer recess in mid-September.

The Congressional Budget Office also warned recently that the US is at risk of a default in October or November unless the Congress raises or suspends the debt limit.

Assuming the debt limit is either raised or suspended, the Treasury said on Monday that it expects to issue almost $1.4 trillion of debt in the second half of the year.

As part of a bipartisan budget deal enacted in August 2019, Congress suspended the debt limit through July 31, 2021.

On Sunday, the debt limit was reinstated at a level covering all borrowing that occurred during the suspension, which had risen to $28.5 trillion aas of the end of June.

The debt limit, commonly called the debt ceiling, is the total amount of money that the government is authorized to borrow to meet its existing legal obligations, including social security and medicare benefits, interest on the national debt, and other payments.