Police said the four leaders, besides a large number of people, raised slogans and gave speeches that amounted to creating hatred between communities at the 'Hindu Dharma Samavesha', organised by the Sene at Yadgir on December 12.
BJP leader Vijay Patil and Siddalinga Swamy of Karuneshwara Mutt were the other two against whom the cases had been booked, they said.
Brandishing a sword, Singh reportedly exhorted Hindu youth to strive to become Hindu fighters till the goal of 'Akhand Bharat' was achieved.
He said Raja Singh made a "controversial and inflammatory speech" at the "Hindu Dharma Samavesha" and two or three people had displayed swords at the function.
"We have taken up a case of unlawful assembly, display of arms and spreading hatred between communities against four persons -- Pramod Kumar Muthalik, Vijay Patil, Raja Singh Thakur and Andola Swamy and others," he said.