The controversial claim raises the prospect of deciphering the written words of one of the most mysterious civilizations known, and so opening a window onto the ancient culture.

The Indus civilisation flourished in isolation 4,500 years ago along the border of what is now eastern Pakistan, but almost no historical information exists about the people and their long-lost community.

Archaeologists working in the region have unearthed a rich hoard of artifacts, including amulets, seals and ceramic tablets, many of which are embellished with the unusual symbols.

The discovery of ancient objects belonging to the Indus has split the scholarly community, with some claiming the symbols form a primitive language and others arguing they are simply pictograms.