Kaupthing Bank hf, Iceland's largest bank, has sought bankruptcy protection from its U.S. creditors, Reuters reported. The Reykjavik-based lender filed a Chapter 15 bankruptcy petition on Sunday with the U.S. bankruptcy court for the Southern District of New York. The filing came after Iceland's Financial Supervisory Authority seized Kaupthing, Glitnir Banki hf and Landsbanki Islands hf, the nation's three largest banks, as the global credit crisis deepened. Glitnir filed on Nov 26 for Chapter 15 protection.