Renowned Indian scholar and rationalist, M M Kalburgi, has been killed after being shot by unidentified men in the southern state of Karnataka, police have said.

Police said on Sunday that two men came to Kalburgi's residence in the town of Dharwad, nearly 400km from IT hub of Bangalore, and shot him after he opened the door.

Kalburgi, a recipient of several literary awards, including the prestigious Sahitya Academy Award, was rushed to the district hospital by his family members but died on the way.

Dharwad City Police Commissioner Ravindra Prasad told Al Jazeera that police was considering it as a case of murder and a "special squad" has been formed to work on the case.

He said the police did not suspect any particular group and that the investigation was under way with a "clean mind".

Modi's deafening silence on activist assassinations

Kalburgi, who was former vice chancellor of Kannada University in the southern town of Hampi, was mired in a controversy in June 2014 for his remarks against "idol worship", which is an important aspect of Hindu belief.

Far-right groups such as the Vishwa Hindu Parishat and Bajrang Dal had filed cases against him and also demanded his arrest for allegedly offending religious sentiments.

Kalburgi had recently asked the police to withdraw armed guards, who were deployed at his house after he received a number of threats over his remarks on idol worship, the International Business Times India reported.

His murder comes months after a social activist Govind Pansare was killed while on a morning walk in the city of Kolhapur in the western Maharashtra state.

The killing is a reminiscent of the murder of rationalist and author Narendra Dabholkar in the western city of Pune in 2013.

It is #Kalburgi today, #Pansare yesterday & #Dhabolkar the day before. What horrors do the morrows hold? — SANJAY HEGDE (@sanjayuvacha) August 30, 2015

Indian news website Scroll.in pointed to a tweet from an account belonging to the Bajrang Dal co-convener in Bantwal, which seemed to issue an open threat to other academics who allegedly hurt Hindu sentiments.

Police Commissioner Prasad told Al Jazeera that he was unaware of the above tweet, but promised to investigate it.

Since the coming to power in May 2014 of the Hindu nationalist Bharatiya Janata Party under the leadership of Narendra Modi, far-right groups have become vocal. The country of 1.2 billion has seen a sharp rise in social tension in the first five months of this year.

Activists and members of civil society have warned the government to rein in such groups.