Greek banks fall 3.4 pct on spreads, deficit revision

ATHENS, April 22 (Reuters) - Greek bank shares fell 3.4 percent on Thursday, as yield spreads of Greek government bonds over German bunds blew out to new a new high and the country's 2009 budget gap was revised upwards by nearly a full point.

At 1000 GMT the Athens bourse's banking index .FTATBNK was losing 3.84 percent to 1,927 points, underperforming the broader Greek market .ATG which was shedding 2.39 percent.

"The spike in yield spreads and credit default swaps and the upward deficit revision by Eurostat are driving bank shares lower," said Takis Zamanis, chief trader at Beta Securities.

"There are worries over the impact on banks' bond portfolios" he said.

The Greek/German 10-year bond yield spread widened to 535 basis points, its widest in 12 years after Eurostat revised last year's budget gap to 13.6 percent of GDP from a previous 12.7 percent.

Shares of National Bank (NBGr.AT) were down 5 percent to 11.7 euros with Alpha (ACBr.AT) losing 2.8 percent. (Reporting by George Georgiopoulos and Lefteris Papadimas)