REYKJAVIK, Iceland—Voters in Iceland have rejected a government-approved deal to repay Britain and the Netherlands $5 billion for their citizens' deposits in the failed online bank Icesave, referendum results showed Sunday.

With about 90% of the votes counted, the "no" side had 59.1% of the votes and the "yes" side 40.9%. The result reflects Icelanders' anger at having to pay for the excesses of their bankers, and complicates the country's recovery from its 2008 economic collapse.

Prime Minister Johanna Sigurdardottir said the results were disappointing but she would try to prevent political and economic chaos ensuing. She said the repayment dispute would now be settled by a European trade court—which could impose harsher terms on Iceland than those rejected in Saturday's vote.

Britain and the Netherlands said they would fight to get their money back. Dutch finance minister Jan Kees de Jager said the referendum result "is not good for Iceland and also not good for the Netherlands."

"The time for negotiations has passed," he said. "Iceland still has the obligation to pay us back. This is now a case for the courts."