Chennai |The Indus valley script remains an unsolved riddle for over a century, Tamil Nadu Chief Minister M K Stalin said here on Sunday and announced a prize of US dollar 1 million to those who decipher it.

Inaugurating a 3-day international conference to mark the centenary of the discovery of the Indus civilisation, Stalin said,"We are still unable to clearly understand the script of the Indus valley civilsation that once flourished."

Efforts are on to this day by scholars to solve the riddle and in order to encourage such efforts, a prize of US dollar 1 million will be provided to individuals or organisations that solves the riddle, he announced.

The Indus civilsation, one of the earliest, is reputed for its urban culture and its script has not been decrypted yet. The fading away of such a civilisation, and its context, also remains a riddle.