Experts say the latest eruption on Friday is the volcano's 'biggest in at least a century' [Reuters]

Nearly a dozen airlines have cancelled flights into Indonesia's main international airport after a volcano in central Java unleashed its most powerful eruption in a century.

The move comes amid concerns that Merapi, about 450km to the west of the Indonesian capital, Jakarta, may erupt again.

Flights to cities closer to Merapi - including Yogyakarta, Solo and Bandung - have also been affected.

The flight cancellations also came just days before Barack Obama, the US president, was due to visit Indonesia.

"Thirty-six flights to and from Jakarta from 11 airlines have been cancelled today. I think it's for safety reasons due to the volcanic ash from Merapi," Sudaryanto, a spokesman for Soekarno-Hatta International Airport, said.

"Safety is good, but actually the ash hasn't reached Jakarta."

Threatening ash

Sudaryanto listed the airlines that cancelled their flights as Singapore Airlines, Air Asia, Emirates, Malaysia Airlines, JAL, Turkish Airlines, Lufthansa, China Airlines, Korean Air, Tiger Air and the local airline Mandala.

Separately, Cathay Pacific said on its website that flights to and from Jakarta had been delayed and would depart on Sunday, "if conditions improve".

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The eruption of Iceland's Eyjafjallajokul volcano in April forced the closure of most European airports for a week and led to the cancellation of over 100,000 flights.

"The volcanic ash presence in the airways surrounding Jakarta could cause severe damage to our aircraft and engines which could impair the safety of our operations including passengers and crew," Azharuddin Osman, director of operations for Malaysia Airlines, said.

Merapi, Indonesia's most volatile mountain, has killed close to 140 people in the last two weeks.

More than 200 others were injured with various degrees of burns, respiratory problems, broken bones and cuts.

Merapi unleashed on Friday a surge of searing gas, rocks and debris that raced down its slopes at highway speeds, mowing down villages and leaving a trail of charred corpses in its path.

Thousands of Indonesians were desperately trying to leave the area surrounding Merapi as officials began preparations to hold mass burials for victims.

Mass evacuations

The Indonesian government has expanded a "danger zone" to a ring 20km from the peak, bringing it to the edge of the ancient royal capital of Yogyakarta, which has been put on its highest alert.

The biggest threat, however, is the Code river, which flows into the city of 400,000 from Mount Merapi, and could act as a conduit for deadly volcanic mudflows that form in heavy rains.

The volcano has killed at least 138 people and continues to shoot ash and gas clouds high into the sky [EPA]

More than 166,000 people were evacuated after everyone living within the declared "danger zone" had been told to leave their homes immediately, though some were reluctant to abandon their livestock.

Racing at speeds of 100km per hour, the molten lava, rocks and other debris can destroy everything in their path.
Merapi's latest round of eruptions began on October 26, followed by more than a dozen other powerful blasts and thousands of tremors.

Scientists and officials have steadily pushed the villagers who live along Merapi's slopes farther from the crater with each new eruption.

Friday's eruption released 50 million cubic metres of volcanic material, with plumes of smoke shooting up more than 10,000 metres, which makes it "the biggest in at least a century" at Merapi, Gede Swantika, a state volcanologist, said.

Merapi killed around 1,300 people in 1930 but experts say the current eruptions are its biggest convulsions since 1872.

Indonesia, an archipelago of 235 million people, is prone to earthquakes and volcanoes because it sits along the so-called Ring of Fire, a horseshoe-shaped string of faults that lines the Pacific Ocean.

Source: Agencies