JAKARTA, May 21 (Xinhua) -- Mount Merapi, the most active volcano in Indonesia, spewed a column of smoke and ash into the air on Monday in the second phreatic eruption this month.

The volcano, located in the borders of Central Java and Yogyakarta province, erupted twice with a column of volcanic material sent up to 1,200 meters high, creating volcanic ash rain in several villages, spokesman of the national disaster management agency Sutopo Purwo Nugroho said on Monday.

"Climbers are prohibited from getting close to the area around the crater as the ground is vulnerable to slide down," the spokesman told Xinhua in a text message.

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.

On May 11, the volcano witnessed a phreatic eruption, spewing a column of volcanic ash 5,500 meters high, and forcing residents living in the slope to flee homes and the closure of the main airport in Yogyakarta province, the agency said.

A 3 km no-go zone has been declared by the volcanology agency.

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