An elderly woman is comforted by a relative as displaced families flee their homes as Iraqi forces battle with Isil militants in western Mosul. Photo: Reuters/Zohra Bensemra

Archaeologists documenting Isil's destruction of the ruins of the tomb of the prophet Jonah say they have made an unexpected discovery which could help our understanding of the world's first empire.

The Nebi Yunus shrine - containing what Muslims and Christians believe to be the tomb of Jonah, as he was known in the Bible, or Yunus in the Koran - was blown up by Isil militants soon after they seized swathes of north Iraq in 2014.

The shrine is situated on top of a hill in eastern Mosul called Nebi Yunus - one of two mounds that form part of the ancient Assyrian city of Nineveh.The Iraqi army retook the area from Isil last month, revealing the extensive damage wrought by the jihadists.

Local archaeologists have said that Isil also dug tunnels deep under the demolished shrine and into a previously undiscovered and untouched 600BC palace. Inside one of the tunnels, Layla Salih, an Iraqi archaeologist, discovered a marble cuneiform inscription of King Esarhaddon thought to date back to the Assyrian empire in 672BC.

While the king's name is not visible on the slab, a historian who has seen photographs of it says phrases are legible which were used only to describe him, in particular his rebuilding of Babylon after his father Sennacherib had it destroyed. There are only a handful of such cuneiforms recovered from the period.

Prof Eleanor Robson, chairman of the British Institute for the Study of Iraq, said: "There's a huge amount of history down there. It is an opportunity to finally map the treasure-house of the world's first great empire, from the period of its greatest success."

Ms Salih, a former curator of the Mosul museum who is supervising a five-man team carrying out the emergency documentation, said she believed Isil looted hundreds of objects before Iraqi forces recaptured the eastern side of the city.

"I can only imagine how much [Isil] discovered down there before we got here," she said. She also warned that the tunnels were at risk of collapsing "within weeks" - burying and potentially destroying the new finds.

Meanwhile, Iraqi forces seized a damaged Mosul bridge yesterday which could link up their units on either side of the Tigris river, as thousands of civilians fled the fighting for Isil's remaining stronghold in the west of the city. (© Daily Telegraph London)

Telegraph.co.uk