Egyptian archaeologists have dashed hopes that a newly-discovered ancient sarcophagus might contain the remains of Alexander the Great, finding instead what appeared to be a mummified family of three swimming in red liquid.

Key points: The 30-tonne coffin is the largest yet found in Alexandria

The 30-tonne coffin is the largest yet found in Alexandria The location of the remains of Alexander the Great remains a mystery

The location of the remains of Alexander the Great remains a mystery The mummies were not in the best condition, only bones remain

Workmen found the black granite tomb this month during construction of an apartment building in the historic Mediterranean port city of Alexandria.

The 30-tonne coffin, the largest yet found in Alexandria, prompted a swirl of theories in local and international media that it may be the resting place of the ancient Macedonian ruler, who founded the city that still bears his name in 331 BC.

Egypt's antiquities ministry had vigorously dismissed the chances of finding Alexander's remains inside the 2,000-year-old sarcophagus, and on Thursday its scepticism was vindicated.

"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," Mostafa Waziri, secretary-general of the Supreme Council of Antiquities, said.

Mr 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.

A general view of the residential area where the coffin was discovered. ( Reuters: Mohamed Abd El Ghany )

Alexander died in 323 BC in Babylon, in what is now Iraq, but his remains were later moved to Alexandria. The exact location of his tomb remains a mystery.

Mr Waziri said it was unlikely the remains found this week belonged to any notable members of the Ptolemaic dynasty (332 BC-30 BC) associated with Alexander the Great, or the subsequent Roman era.

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

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

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

The sarcophagus in Alexandria is the latest of a series of interesting archaeological finds this year in Egypt.

Others include a 4,400-year-old tomb in Giza and an ancient necropolis in Minya, south of Cairo.

An archaeologist stands atop the sarcophagus ( Reuters: Mohamed Abd El Ghany )

Reuters/ABC