A 4,000-year-old clay tablet from ancient Mesopotamia revealing details of the ark before Noah was on Thursday displayed at the British Museum in London.

Dr Irving Finkel, an expert on ancient Mesopotamian and cuneiform script with the British Museum, said the clay tablet was "one of the most important human documents ever discovered."

Finkel recently deciphered the tablet which is light brown in color and about the size of a smartphone.

According to the language on the tablet, the boat was a round vessel, and the surface area would have been 3,600 square meters, with walls six meters high. The walls would then have been coated with bitumen.

"It was gigantic, it works out at about two thirds of a football pitch," said Finkel.

"It would have been ideal, it would never sink and it would be a light boat to save all the animals," he added.

This was a giant version of a craft which the Babylonians knew very well, Finkel pointed out, in daily use up to the late 20th century to transport people and animals across rivers.

Finkel said he was "107 percent certain" that the ark described in the tablet had never been built.

He said the cuneiform text was written in about 1750 BC, and is part of a much longer Babylonian story about the flood and what led up to it, also known from the Book of Genesis in the Bible which was written much later.

Later in the year, there will be a television documentary inspired by the discovery of the tablet, showing workers attempting to build it from the instructions on the tablet.