DENPASAR, Indonesia (Reuters) - Thousands of residents were evacuated from villages near an active volcano on the Indonesian island of Bali, officials said on Friday, as the alert status was raised to the highest level, meaning an eruption could be imminent.

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Authorities warned tourists and residents to avoid camping or hiking within a 9 km (6 mile) radius of the crater as seismic tremors rattled some areas and smoke rose above one of the world’s most popular tourist spots.

“Volcanic activity remains high and there are indications of magma rising to the surface and causing tremors,” said Sutopo Purwo Nugroho of the National Disaster Management Agency.

“There should be zero public activity within the specified radius in case there is an eruption,” Nugroho said.

However, flights at Bali’s international airport were operating as normal and there was little disruption to tourism operators across the rest of the island, authorities said.

Nearly 10,000 people have been evacuated so far and that number was expected to rise, officials said.

Others packed their belongings into trucks for evacuation, while more stopped to watch as clouds of white smoke rose from the crater, which is around 3,000 meters (9,840 feet) above sea level.

Indonesia straddles the “Pacific Ring of Fire”, where several tectonic plates meet and cause 90 percent of the world’s seismic activity, according to the U.S. Geological Survey.

Indonesia has nearly 130 active volcanoes, more than any other country.

A series of eruptions at Mount Agung between 1963 and 1964 killed more than 1,000 people and injured hundreds.