New York: The top credit rating of Europe's bailout fund depends on additional financial backing from Germany and the other three remaining AAA-rated Eurozone countries, Standard & Poor's said on Friday.

The fund, also known as European Financial Stability Facility (EFSF), has its AAA rating at risk after S&P stripped two of its guarantors, France and Austria, of their top credit ratings. If downgraded, the EFSF could face higher borrowing costs, reducing its firepower to rescue troubled countries in the region.

Raising cash buffers

"If you have a greater commitment from the other countries, then the EFSF could retain its AAA rating," John Chambers, the chairman of S&P's sovereign rating committee, told Reuters Insider in an interview. "If you've lost two of the six AAA guarantors, either they need to increase the backing from the four remaining AAA guarantors or they need to raise some cash buffers," Chambers said.

Another option would be that the fund raises collateral to cover its outstanding obligations. Germany and France are the main guarantors of the EFSF.

Chambers also said the European Central Bank's (ECB) recent measures to increase liquidity to banks promoted a substantial monetary easing in the Eurozone, which was "good news" for the ratings. Some banks may have used the low-cost money from the ECB to invest in government bonds, he added.