Hours after being allowed to return home, thousands of people were evacuated from villages around Mount Merapi today as the volcano, whose activities had calmed in recent days, emitted a giant gas cloud.

Authorities in Java believe an eruption is now imminent and have hoisted the alert level back up to its highest status again.

Mount Merapi, one of Indonesia’s most dangerous and unpredictable volcanoes, has been threatening a full-scale eruption for more than a month, putting the lives of those who farm its fertile soil or quarry its minerals on hold.

Today, the searing gas clouds stretched for more than four miles downhill from the pool of lava at its cone - the furthest distance since the alert was first raised on May 13.

"The situation is quite serious. It is life threatening," said Yousana Siagian, head of the government’s Vulcanology and Disaster Mitigation Centre said.

One village was almost enveloped by the deadly gas cloud and another, four miles (7km) from the crater, was covered in a blanket of ash an inch thick.

Budiono, the chief of Ngargosoko, a village six miles (10km) from the summit, told of the frustration and panic taking hold among locals.

"The villagers are confused. They said it was safe, but hot clouds re-emerged. One thing is for sure, we have readied ourselves to evacuate anytime,"he said.

Edy Susanto, a district official, said that about 12,000 people in the Magelang district, on the mountain’s west side, had been ordered to leave. Some were awaiting trucks to take them to shelters as dusk fell.

Despite the danger, many of have stayed put over the last month, citing the need to look after homes, crops and animals.

Merapi erupted in 1994 killing more than 60 villagers and before that in 1930 when about 1,300 people died.

The island was visited by tragedy last month when an earthquake measuring 6.3 hit the city of Yogyakarta, killing more than 5,800 people.

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