DUBAI- Japan's Mizuho Financial Group, a bank initially appointed as bookrunner for a U.S. dollar-denominated bond by Qatar, has withdrawn from the transaction, it said on Tuesday.

Qatar issued $12 billion in bonds last week, its first international debt sale since a boycott imposed by some of its Arab neighbours last year when they accused the country of supporting terrorism. Qatar firmly denies that charge.

International banks with business in the Gulf have adopted a cautious stance since the crisis to maintain relationships on both sides of the dispute.

(Reporting by Davide Barbuscia, editing by Louise Heavens) ((Davide.Barbuscia@thomsonreuters.com; +971522604297; Reuters Messaging: davide.barbuscia.reuters.com@reuters.net))