The matter came to light when Congress workers came to garland the picture of Mahatma Gandhi.
As India celebrated the 150th birth anniversary of Mahatma Gandhi, an urn containing his ashes was found missing from Bapu Bhawan situated inside the premises of the sprawling Laxman Bag museum in Madhya Pradesh's Rewa.
The unidentified people who stole the ashes also wrote defamatory words on the photograph of the Father of the Nation that was placed on a hoarding-like structure inside the Bhawan.
The matter came to light on Wednesday, when the Congress leaders reached the Laxman Bag museum premises to garland the picture of Mahatma Gandhi.
The workers alerted cops, who rushed to the spot and cleaned the defamatory words written on the photograph.
"A case has been registered under Sections 153B (imputations, assertions prejudicial to national integration) 504 (intentional insult with an intent to provoke the breach peace) and 505 (statements conducing public mischief) against unidentified persons and investigations are underway," Rewa's Superintendent of Police Abid Khan said.
Sources said that the entire premises of the museum were painted a few months back and the same colour seem to have been used to deface Gandhi's photograph.
Senior Congress leader and former Madhya Pradesh chief minister Digvijaya Singh expressed his disappointment on twitter.
Also expressing his shock at the development, the Mahatma's great-grandson Tushar Gandhi, in a statement, said: "Just heard the news that someone/people stole the funeral ashes of my great grandfather kept in a shrine at Gandhi Bhavan in Rewa Madhya Pradesh. Wish he wasn't the father of the nation, wish he wasn't Mahatma. Wish he was only my great grandfather."
(with inputs from IANS)