Archaeologists in Egypt have found the symbolic tomb of the ancient Egyptian god Osiris buried deep underneath one of the Giza pyramids.

According to Egyptian archaeologist Zahi Hawass, the discovery of the granite sarcophagus became possible after water levels inside the pyramids sank.

Mr Hawass said the sarcophagus, which is estimated to date from 500 BC in the New Kingdom, was surrounded by the remains of four pillars built in the shape of a hieroglyphic House of Osiris.

Ruler of the underworld

Osiris was one of the most important gods of ancient Egypt who according to mythology was murdered by his wicked brother Seth.

He was buried by Isis, his sister-wife, and brought back to life as judge of the dead and ruler of the underworld.

According to Mr Hawass, Herodotus, the famous ancient historian, mentioned that this tomb existed in the middle of the 5th century BC, but it has never been possible to access it because of high water levels.

Deep underground

After the dirt and water were cleared from the shaft located between the Sphinx and the Pyramid of Chefren (Khafre), archaeologists found three underground levels, with the submerged Osiris sarcophagus at the lowest, about 30 metres below the surface.

"I never excavated this shaft because it was always full of water. But when the water went down about a year ago, we started the adventure," Mr Hawass told Reuters news agency.

"Many people believed there were tunnels going to the Sphinx and another leading to the Great Pyramid but only when we sent a young boy into a tunnel in the west wall did we find this exciting discovery," said Mr Hawass.

The excavation also unearthed 3,000-year old bones and pottery found in the underground water.