The statue was found disfigured this morning, police said.
The installation of the statue at the school, where the celebrated writer once studied, had kicked up a controversy earlier with the Kottakkal municipality refusing to give sanction, stating that school authorities had not obtained prior permission.
The statue was later installed following the intervention of local MLA Abdusamad Samadani.
Senior Congress leader and Kerala Electricity Minister Aryadan Mohammed, in a statement, condemned the disfiguring of the statue.