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 late Thursday, authorities said, raising the volcano's alert status to the highest level.

As of 9:45 am (0145 GMT) Friday, "seven international flights had been cancelled, six of them are Jetstar flights bound to Australia and one Air Asia flight to Kuala Lumpur," Bali's Ngurah Rai International Airport spokesman, Andadina Dyah, said in a statement.

Several other flights -- both domestic and international, including to Thailand, Singapore and Australia -- have been delayed, it said.

The local airport in Maumere, on Flores, the closest to the volcano, has not been affected by the ash, according to the transportation ministry.

"The ash column was observed grey to black with thick intensity," Indonesia's volcanology agency said in a statement about the eruption, which began at around 11:00 pm on Thursday.

There were no 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 (four to five miles) 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."