Researchers from the institute and Germany's Berlin Speleoclub have surveyed and discovered the system of 11 caves for two months and found the caves formed after an eruption.

The longest Doi (Bat) Cave was separated by a geological collapse and rupture that created two additional caves called Bat Cave No 1 and Bat Cave No 2.

The largest section of the cave is about 426m long, 4m high and 10m wide. The explorers consider it as the longest lava cave in the Southeast Asia as Gua Lawah Cave in Indonesia, the current longest one, is 400m long.

In some lava caves, researchers discovered many species of animals such as bats, spiders, centipedes, scorpions, cave crickets, flies, ferrets and frogs.

German scientists intend to publish these findings in English, including maps and descriptions of the cave complex, in publications of the Berlin Speleoclub.

The local authorities have called on people to be aware of protecting the complex and stop catching bats in the cave to preserve ecological environment of the site.