Moody's Investors Service warned Thursday that many European banks and global investment banks are likely to see their credit ratings further downgraded by the agency.

"The expected decline of bank ratings reflects the acceleration of interrelated pressures on the banking sector since the second half of 2011," said Greg Bauer, Moody's global banking managing director, in a statement.

"These pressures most immediately affect global capital markets intermediaries and European banks," Bauer said.

The New York-based agency said it might make the move because of deteriorating sovereign creditworthiness, particularly in the euro area, elevated economic uncertainty and funding spreads, and reduced market access at a time when many banks face large debt maturities.

Moody's said it expects to place the ratings of "a number of banks" under review for downgrade during the first quarter of 2012, in order to assess the effect of these trends on bank credit profiles.