Geologists have discovered the world largest canyon below the ice that covers the Antarctic region.

The chasm measures 1,000km long, and it is around 1km deep in some places, the Geology monthly reported.

The as-yet unnamed canyon was discovered by examination of satellite imagery.

The canyon is believed to have been carved by water, but it is not known whether it was formed before the Antarctic ice sheet grew or after.

Experts believe the canyon may be connected to another previously undiscovered, underground feature - a vast subglacial lake with a surface area of 1,250 square km, reported Lenta.ru, a Moscow-based online newspaper.