JAKARTA: The threat from an Indonesian volcano that has erupted more than half a dozen times this week is not over, the archipelago's top volcanology official told AFP, as the crater belched another ash tower on Saturday.

Mount Ruang, located in Indonesia's outermost region of North Sulawesi province, started erupting late Tuesday, prompting authorities to evacuate thousands on islands near the stratovolcano and closure of the nearest international airport.

The volcano erupted again before midnight Friday and again on Saturday afternoon, spewing an ash column 250 meters (820 feet) above its peak, the latest of a wave of volcanic activity, the volcanology agency said. That forced the country's volcanology agency to warn that major eruptions could still take place, despite the crater calming since it stirred a spectacular mix of lava, ash and lightning earlier in the week, raining down molten rocks on nearby villages.

"With volcanic earthquakes recorded, this crisis is not over yet," agency head Hendra Gunawan told AFP. "It indicates magmatic fluid supply is still moving from the depth to the surface. So it's not surprising if eruptions still occur."

The volcano, with a peak 725 meters above sea level, is currently the only one of Indonesia's more than 100 volcanos at the highest alert level of a four-tiered system. Authorities have kept a six-kilometer (3.7-mile) exclusion zone around the volcano.

More than 6,000 residents of neighboring Tagulandang island, home to around 20,000 people, were evacuated outside the exclusion zone, a local official said Friday. Authorities previously estimated more than 11,000 people would need to be evacuated because of the volcanology agency's warning of volcanic rocks, hot clouds and lava flows.

Residents were advised to wear masks to avoid respiratory problems, the agency said in a statement. The stratovolcano's latest activity also prompted authorities to extend the closure of Sam Ratulangi international airport in the provincial capital of Manado, more than 100 kilometers away.

The airport, initially set to reopen Saturday, will remain closed until Sunday as volcanic ash from Mount Ruang was detected around it, Ambar Suryoko, head of the Manado region airport authority, said in a statement. Indonesia, a vast archipelago nation, experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire". — AFP