Although the Greek debt crisis led Moody's Investors Service to downgrade two major French banks Wednesday, French President Nicolas Sarkozy and German Chancellor Angela Merkel have reaffirmed that Greece should stay in the 17-nation euro zone.

The consensus emerged after a Wednesday conference call the two leaders had with Greek Prime Minister George Papandreou.

But Sarkozy and Merkel told the Greek prime minister that Athens must put in place strict and effective measures previously agreed upon with European Central Bank and International Monetary Fund as part of the bailout package conditions.

"That is a prerequisite for the payment of future tranches of the program. ... The Greek prime minister has reaffirmed the absolute determination of his government to take all necessary measures to put into practice given commitments in its entirety," Papandreou's spokesman told The Wall Street Journal.

Among the new cost-cutting measures that Germany and France supported to ensure that Greece would meet its deficit reduction targets is a new property tax.

To further help Greece address its fiscal problems, the leaders agreed to expand the scope of the zone's current rescue fund, the European Financial Stability Facility, to empower it to purchase bonds in the secondary market. The facility's lending capacity was earlier increased to 440 billion euros ($602 billion).

Both measures, however, need the approval of some European parliaments.

Moody's downgraded on Wednesday the ratings of Credit Agricole and Societe Generale by one notch because of the impact of a possible Greek debt default on the lenders' finances. The ratings agency also placed on review another big French bank, BNP Paribas.