BERLIN, Aug 21 (Reuters) - New German bonds with a 30-year maturity were issued with a negative yield for the first time in an auction on Wednesday, data from the Bundesbank showed.

The average yield in the auction was -0.11%.

Thirty-year bond yields across major markets have tumbled this year as worries about weak growth and speculation about central bank easing drives investors into longer and longer-dated maturities to grab a few extra basis points of yield. (Reporting by Michelle Martin; Editing by Virginia Furness)