GRAPHIC: Experts were driven from the site of an ancient Egyptian sarcophagus after opening it unleashed a putrid stench.

The granite casket, which had been sealed, was thought to be the largest ever found in the Egyptian port city of Alexandria. Weighing more than 30 tonnes it was found at a building site, five metres below ground level.

Experts had only opened the lid by 5 centimetres when they were forced to leave by the unbearable smell, apparently caused by fetid liquid, the BBC reported.

After returning to lift the lid with the help of the military, they found the skeletal remains of three people.

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MINISTRY OF ANTIQUITIES The granite casket, which had been sealed, was thought to be the largest ever found in the Egyptian port city of Alexandria.

"We found the bones of three people, in what looks like a family burial... Unfortunately the mummies inside were not in the best condition and only the bones remain," secretary-general of the Supreme Council of Antiquities, Mostafa Waziri, told media.

​Waziri said some of the remains had disintegrated because sewage water from a nearby building had leaked into the sarcophagus through a small crack in one of the sides.

An Egyptian archaeological mission from the Supreme Council of Antiquities uncovered the ancient tomb, which dates back to the Ptolemaic period.

The period started with the death of Alexander the Great in 323BC and ended with the death of Cleopatra and the Roman conquest in 30BC.

EGYPT ANTIQUITIES MINISTRY The ancient sealed sarcophagus was opened to reveal the remains of three people, covered in a red-brown liquid understood to be sewage water that leaked into the casket through a crack.

The opening of the sarcophagus dashed hopes that it contained the body of Alexander.

Neither did the bodies belong to any other notable ruler in the Ptolemaic period (332 BC-30 BC) associated with Alexander the Great, or the subsequent Roman era, Waziri said.

MINISTRY OF ANTIQUITIES Also found was an alabaster head, thought to belong to the tomb's owner.

A rough alabaster head of a man was also found in the tomb. It is thought to be of the tomb's owner.

The prospect of opening the long-sealed sarcophagus had stirred fears in Egyptian media that it could unleash a 1000-year curse.

"We've opened it and, thank God, the world has not fallen into darkness, said Waziri.

"I was the first to put my whole head inside the sarcophagus... and here I stand before you ... I am fine."