Fitch reiterates U.S. downgrade warning

The U.S. Treasury Department will exhaust all of its borrowing options and run dry of cash to pay its bills by late March or early April if Congress does not raise its borrowing limit, the Congressional Budget Office has said.

Fitch's head of sovereign ratings James McCormack told Reuters that even if Washington then continued to make interest payments on its main government bonds, not meeting other domestic obligations "would not be compatible with 'AAA' status."

During the debt ceiling showdown in August 2011, Standard & Poor's stripped the United States of its highest rating. It has since then kept a slightly less sterling grade of AA+ on the world's largest economy. Like Fitch, Moody's Investors Service has maintained its top credit rating on the United States.

(Reporting by Marc Jones, editing by Karin Strohecker)