After the cut in credit rating of several euro area countries, including the AAA-rated France and Austria, by Standard and Poor's over the weekend, the European Financial Stability Facility (EFSF) is at risk of facing a similar downgrade to its top rating, yet a senior euro zone official said there are two ways to retain the top rating.

The first way is to increase the guarantees from the four remaining top-rated countries, namely Germany, Netherlands, Finland and Luxembourg, to replace loss in guarantees from France and Austria.

The second option is to reduce the lending capacity of the EFSF to 180 billion euros from its full capacity of 440 billion euros.

This week the EFSF is set to auction 1.5 billion euros of six-month bonds in the first test after the S&P cut.