BUDAPEST—Hungary's gross public debt jumped to a four-year high of 85.1% of gross domestic product at the end of June, central bank data published Monday showed.

Gross public debt calculated under the European Union's Maastricht criteria was 81.7% of GDP a year earlier and 85.6% of GDP in June 2010 when the current government first gained power and the forint, the Hungarian currency, weakened significantly against core currencies amid Europe's continuing economic crisis.

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