Ruang island is about 100 km from Manado, the capital of North Sulawesi province in the north-central region of the sprawling Indonesian archipelago. It home to more than 800 residents, most of whom evacuated following the recent eruptions.

Indonesia's Ruang volcano spewed explosive incandescent lava into the night sky early on Tuesday as lightning flashes lit up its crater, prompting authorities to raise the alert status and warn of a possible tsunami.

The Center for Volcanology and Geological Hazard Mitigation (PVMBG) warned residents living on Tagulandang island, the island closest to the volcano, that a tsunami could be triggered by volcanic material collapsing into the ocean.

The warning was issued on Tuesday morning, with PVMBG official Hetty Triastuty saying it remained in placed as of the afternoon.

The agency raised the alert status of Ruang to the highest level following the early morning eruption, urging residents not to go near the volcano.

Tuesday's eruption follows a series of eruptions earlier this month that forced hundreds to evacuate, and the airport in the provincial capital of Manado to close. That eruption also caused damage to some homes. At the time, the volcanology also issued a warning about the potential for a tsunami.

Footage shared by Indonesia's disaster mitigation agency showed strikes of lightning flashing above Ruang's crater, as fiery red clouds of lava and rocks were projected into the air and rained down around the island.

The agency said the eruption column reached 5 kilometres (3.1 miles) high, and urged any remaining residents within a 7-km, previously 6-km, radius to immediately evacuate, warning of possible further "explosive eruptions".

Ruang island is about 100 km from Manado, the capital of North Sulawesi province in the north-central region of the sprawling Indonesian archipelago. It home to more than 800 residents, most of whom evacuated following the recent eruptions.

The eruption corresponded with a spike in seismic activity and deep volcanic earthquakes, the disaster agency said.

Authorities downgraded the status level to level 3 last week before bumping it up again to level 4 on Tuesday.

Indonesia straddles the so-called "Pacific Ring of Fire," an area of high seismic activity where multiple tectonic plates meet.