Greek banks extend losses, down 11 pct on concerns about aid

Greek banks stocks tumbled more than 11 percent on Tuesday, heading for the biggest one-day drop in years, on concerns that Germany could be an obstacle to providing financial aid to Greece.

"There is uncertainty about when and how the aid mechanism will be activated," said Takis Zamanis, Athens-based trader at Beta Securities.Nikos Galoussis, Athens-based analyst at Kappa Securities.

At 1326 GMT, the Athens bourse's banking index <.FTABNK> was down 11.2 percent to 1,640.31 points with bellwether National Bank <NBGr.AT> falling 10.2 percent and EFG Eurobank <EFGr.AT> down 11.4 percent.

Tuesday's selloff in Greek bank shares represented a 2.7 billion euro wipeout in market capitalisation.