An Indonesian volcano on Sunday saw its biggest eruption, sending huge clouds of ash 3,500 meters (11,500 feet) into the sky, official said.

The volcano erupted again this morning, the biggest since late June. It spewed rocks and ash, government vulcanologist Kristianto told AFP.

We have informed the airport to be on alert as the ash is quite high this time. But so far, flights are not affected yet and the airport is not closed, Kristianto said.

The volcano is still in eruption phase. We can't predict whether the activity will slow down or if there will more eruptions, he added.

The 1,580 meters Mount Lokon is one of Indonesia’s 129 active volcanoes. Mount Lokon was last erupted in 1991.

According to disaster management agency more than 5,200 people have been evacuated to temporary shelters. The volcano was erupted on Thursday June 14, at
10:46 p.m. and its alert status was placed on the highest level, officials said.

Residents were warned on Wednesday to stay far away from the 5,741-foot (1,750-meter) volcano, which has been on high alert for a week, with small daily outbursts. About 2,000 had already fled before Thursday's eruption and more than 33,000 people live along the fertile slopes of Mt Lokon.

A 2.2 mile (3.5k) evacuation zone has been established in case of a bigger eruption, and about 28,000 people live within that zone.

A vast archipelago of 235 million people, Indonesia is prone to earthquakes and volcanoes as it sits atop the Pacific Ring of Fire, a horseshoe-shaped string of fault lines that edge the Pacific Ocean.

A Swiss hiker was killed and thousands were forced to flee their homes during Mt Lokon's last major eruption in 1991.