Washington: Credit rating agency Standard & Poor's said on Thursday that there is a 50 per cent chance it will downgrade the US government's credit rating within three months because of the congressional impasse over approving an increase in the debt ceiling.

In a statement, the rating agency said it is placing the United States on a credit watch with at least a one-in-two likelihood that it will lower the country's debt rating within the next 90 days.

The S&P action marked the second credit warning in the past two days. On Wednesday, Moody's Investors Service said it is reviewing the government's triple-A bond rating because it believes the White House and Congress are running out of time to raise the nation's $14.3 trillion (Dh52.5 trillion) borrowing limit and avoid default.