A 1.4-kilogram giant rat - probably a species new to science - found in the "lost world" of Foja in western New Guinea.
Photo: Bruce M Beehler

Researchers in a remote jungle in Indonesia have discovered a giant rat - five times the size of a typical city rat - and a tiny possum that are apparently new to science.

Unearthing new species of mammals in the 21st century is very rare. The discoveries by a team of American and Indonesian scientists are being studied further to confirm their status.

The animals were found in the Foja mountains rainforest in eastern Papua province in a June expedition, said US-based Conservation International, which organised the trip along with the Indonesian Institute of Science.

"The giant rat is about five times the size of a typical city rat," said Kristofer Helgen, a scientist with the Smithsonian Institution in Washington.

"With no fear of humans, it apparently came into the camp several times during the trip."