Several big European banks including Credit Agricole and Royal Bank of Scotland on Thursday posted 2011 losses as the fallout from Greek debt crisis rippled throughout the region.

Credit Agricole SA (EPA:ACA) had a net loss of 3.07 billion euros ($4.06 billion) in the fourth quarter, its worse result ever.

The French bank, which owns Greek bank Emporiki, had a 220 million euro ($292 million) charge related to Greece's debt.

Its stock fell nearly four percent to 4.81 euros Thursday morning.

The Royal Bank of Scotland (NYSE:RBS) had a loss of nearly 2 billion pounds ($3.14 billion), as it marked down Greek bonds by 79 percent, or 1.1 billion pounds ($1.73 billion), for the year.

"Our job is to defuse the biggest-ever time bomb put in a banking balance sheet," said RBS CEO Stephen Hester, during an earnings call. Hester also defended the payout of nearly 1 billion euros in bonuses to employees, saying it was necessary to retain talent.

Shares of RBS were up 5.39 percent in pre-market trading to $9.

Germany-based Commerzbank (ETR:CBK) took a 700 million euro ($930 million) loss related to Greece's sovereign debt in the fourth quarter. Its shares fell nearly 6 percent to 1.95 euros ($2.59).

The write-downs come as the banks are reducing their balance sheets in the face of economic slowdown throughout the region. The European Banking Authority has required that the banks keep more funds in reserve in case of more stress in the market, which has put further pressure on the companies.

Greek's government is debating Thursday to approve a deal that would wipe out 107 billion euros ($142 billion) from its private debt.