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Photo taken on June 2, 2018 shows the Mount Merapi in Magelang, Indonesia. Indonesia's most active volcano of Mount Merapi in Java island spewed a column of volcanic ash 6 km into the air on Friday and a top alert notice has been unveiled for passenger planes, a government official disclosed. (Xinhua/Supriyanto)

JAKARTA, June 1 (Xinhua) -- Indonesia's most active volcano of Mount Merapi in Java island spewed a column of volcanic ash 6 km into the air on Friday and a top alert notice has been unveiled for passenger planes, a government official disclosed.

Mount Merapi situated in the borders of Yogyakarta province and Central Java province erupted at 8:20 a.m. Jakarta time with volcanic spreading ash to the west of the crater, spokesman of national disaster management agency Sutopo Purwo Nugroho said.

"Vona (Volcano Observatory Notice for Aviation) has been issued with red color," he told Xinhua, referring to the highest level of the notice meaning planes are not allowed to pass through the volcano area.

Still, its level could change in line with the development of the latest situation, Sutopo cited.

"The people living in the volcano effect vulnerable-zone III are warned to boost alertness," he said.

On May 24, Mount Merapi burst 6 km volcanic ash to the sky, releasing poisonous gas, including H2S and CO2, into the air, according to the volcanology agency.

The alert status of the volcano has been scaled up to the third highest with no-go zone in the radius of 3 km from the crater, according to the agency.

Mount Merapi is located about 28 km north of Yogyakarta city, which has a population of 2.4 million and thousands of people live on the flanks of the volcano.

Mount Merapi, one of Indonesia's 129 active volcanoes, has regularly erupted since 1948. In November 1994, pyroclastic flow from a large eruption killed 27 people, and another major eruption occurred in 2006.??