Indonesia's volcanology agency has raised alert level of a volcano in East Java, Mount Bromo, and declared dangerous zone of 2.5 km from the crater, officials said on Wednesday.

Indonesia has issued a "red alert" for an eruption at Mount Bromo volcano in eastern Java, less than a month after Mount Merapi volcano killed more than 300 people. [Xinhua]

The raise of the alert level comes as Indonesia has conducted relief works after the eruption of Mount Merapi volcano in Central Java that killed more than 320 people and displaced over 400,000 others. The volcano still threats the people as it remains on top alert. "We have raised alert level of Bromo to the top since Yesterday (Tuesday) as the mount seismic activity has risen,"head of Indonesia's Volcanology Agency Surono told Xinhua.

Mount Bromo of 2,329 meters high had entered the phase of eruption since last week, the mount has shot ash containing debris and other material since, but it was not at the dangerous level Agus Budianto, head of sub-unit of volcano observation at the agency said.

Mount Bromo was rare to spew hot gas and ash far from the crater as it was happened during its eruption in 2004, where the volcanologist only declared dangerous zone only one kilometer from the crater and killed only two tourists, he said.

So far the energy unleashed by Bromo was still at the level of its eruption in 2004, just for anticipation of the possibility of increasing the volcanic activity the volcanologist declared dangerous zone at more than that in 2004, 2.5 km, said Budianto.

Mount Bromo is one of Indonesia's most active volcanoes. Indonesia lies in a quake-prone zone called the Pacific Ring of Fire, and now has 129 active volcanoes.