Mount Lewotobi Laki-Laki, a 1,703-metre (5,587-foot) twin-peaked volcano on the tourist island of Flores, erupted for 11 minutes and nine seconds, authorities said.

"The ash column was observed grey to black with thick intensity," Indonesia's volcanology agency said in a statement about the eruption that began at 22:56 pm (1456 GMT).

There were no immediate reports of damages to nearby villages, but the agency warned residents of the potential for volcanic mudflow due to heavy rainfall.

The long eruption prompted the country's geological agency to raise the volcano's alert level to the highest of the four-tiered system.

Authorities imposed an exclusion zone between seven and eight kilometres around the volcano, the agency added.

In November, Mount Lewotobi Laki-Laki erupted multiple times, killing nine people, cancelling scores of international flights to the tourist island of Bali and forcing thousands to evacuate.

Laki-Laki, which means "man" in Indonesian, is twinned with a calmer volcano named after the Indonesian word for "woman".

Indonesia, a vast archipelago nation, experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire."