Researchers have unearthed the remains of at least nine primitive human ancestors in Ethiopia, believed to have lived about 4.5 million years ago.

The fossils - fragments of teeth, jaw, hands and feet - all belong to the same species - A. ramidus (Ardipithecus ramidus) - first discovered about a decade ago.

A. ramidus is thought to be the oldest forerunner of modern man - looking more like a chimpanzee than a human.

The fossils were found in Ethiopia's northern Afar region, near the border with Djibouti. Details are reported in Thurday's edition of the British journal, Nature.

Researchers, led by Sileshi Sema of the CRAFT Stone Age Institute at Indiana University, say the fossils are significant, indicating these human ancestors walked upright on two feet and ate a plant-based diet.

Some information for this report provided by AFP and Reuters.