Credit Agricole shares fell 4.8 percent to ¤9.48 ($11.62) after it said the outlook for its Greek subsidiary this year and next is worse than it forecast in October.

Its Emporiki Group subsidiary is not expected to make a profit before 2012, and will cost Credit Agricole ¤400 million ($490 million) in writedowns, the bank said Tuesday.

That has renewed worries that have been plaguing global markets in recent months. Traders are concerned that mounting sovereign debt across Europe, particularly in Greece, Spain and Portugal, would disrupt a global economic recovery and lead to a fresh round of losses for banks holding those governments' debt.

A June report by the Bank for International Settlements said French banks were the most exposed to Europe's laggards, lending $493 billion to Spain, Greece, Portugal and Ireland, just above the $465 billion lent by German banks, according to end-2009 figures.

Meanwhile, shares in BNP Paribas were trading down 2.9 percent at ¤48.87 in Paris afternoon trading after Fitch Ratings cut its rating to AA-.

The agency said it made the downgrade because the eurozone's largest bank by deposits had a "relatively high" exposure to corporate and investment banking.

Analysts mostly dismissed the report's importance, saying investors may have used it to sell shares after gains last week. Alessandro Roccati from Macquarie said he doesn't "understand the logic" behind it and Ingo Frommen, an analyst at German bank LBBW, said he doesn't agree with it.

"BNP is one of the winners of the financial crisis," he said.

Societe Generale shares were down 4.7 percent at ¤37.04 over fears of its exposure to Eastern Europe.

Romanian Environment Minister Laszlo Borbely said in an interview with Mediafax news agency the government was considering introducing a banking tax.

Frommen said investors were worried the move could hurt SocGen, which owns BRD, one of Romania's largest banks.