Three boys, including two who are below 18 years, have been taken into custody from Kollam district, a top police official told PTI.
The three have been brought to Thiruvananthapuram and are being questioned.
The film's producer Anwar Rasheed, who had filed online complaint, had appeared before the investigating officials yesterday and his statements were recorded.
The hugely popular "Premam", helmed by Alphonse Puthren, had suffered a setback with the pirated version being circulated on internet, hitting its revenues.