A volcanic eruption in Indonesia has prompted an aviation warning in Australia, after ash spewed some 2 kilometres into the sky.

Indonesia's Semeru volcano, Java Island's tallest mountain, erupted on Wednesday morning, local time, prompting authorities there to raise the threat level to its highest.

The country's volcanology agency said ash clouds reached some 5.6 km into the sky, roughly 2 km higher than the mountain peak, adding residents should keep to a 2.5 km distance away for safety.

The Australian Bureau of Meteorology's Volcanic Ash Advisory Centre (VAAC) issued a red aviation alert following the eruption.

The VAAC said the ash was "partially identifiable on satellite imagery".

No flights have been cancelled between Australia and Denpasar airport because of the eruption.

At m

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