NANJING - Scientists have announced the discovery of a forest in North China preserved under a layer of volcanic ash deposited nearly 300 million years ago.

The fossil forest, located in the Inner Mongolia autonomous region, is compared to the Italian city of Pompeii in a paper published Tuesday on the website of US journal Proceedings of the National Academy of Sciences. Pompeii was buried under ash after a volcanic eruption in AD 79.

The subtropical forest covers an area of 20 sq km and researchers have been able to reconstruct 1,000 sq meters of its trees and plants, said Wang Jun, head of the research team and a member of the Nanjing Institute of Geology and Paleontology under the Chinese Academy of Sciences.

It is in good condition as the volcano erupted for only a few days, sparing the plants from too much force and preserving many of them the way they were, Wang said.

After the forest was discovered a decade ago, researchers found trees still standing upright with leaves, branches and trunks intact in an ash layer dating back to 298 million years ago.

The group of scientists, including Hermann Pfefferkorn from the University of Pennsylvania, worked with a painter to reconstruct what the forest areas would have looked like.