The Best Director award in the same category went to Asa Helga Hjorleifsdottir of Iceland for the film 'Swan'.
The prize money for best film and best director were Rs 51 lakh and Rs 21 lakh respectively, the organisers said.
'Los Perros' is directed by Marcela Said, one of the most respected contemporary film makers whose films have been awarded in many important festivals.
Handing over the best film award to the French guests at a glittering function tonight, veteran actor Biswajit Chatterjee said, "This film festival is going bigger every year and I think the prize money in best film category is the highest in the country."
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In the Asian Select (Netpack award), Nepalese film 'Goodbye Kathmandu' by Nabin Subba won the honours as the best film.
In the Competition on Indian Language section, the Hiralal Sen Memorial Award, instituted in the death centenary of one of India's first film makers, was given to Dr Bijukumar Damodaran for his film the 'Sound of Silence' with a citation and prize money of Rs 5 lakh.
The Jury Special Mention Award in the section went to Pathumma directed by Panchakshari.
In the documentary films section, 'Mrityubhoj' (The Death feast) by Akanksha Sood got the coveted Golden Royal Bengal Tiger trophy and an award money of Rs 1 lakh.
West Bengal Panchayat and Rural Development Minister Subrata Mukherjee, who handed over two awards, said the festival has truly assumed global proportions with the participation of international film makers.
Welcoming the delegates, West Bengal Youth Affairs and Sports Minister, Arup Biswas said, "KIFF is another feather in cap for the state after the Durga Puja Carnival and U-17 FIFA World Cup."
Minister of State for Information and Cultural Affairs, Indranil Sen also said the 23rd KIFF has turned out to be one of the important film events in the world.
KIFF Director Yadav Mondal said several contemporary works by renowned and upcoming filmmakers of the country and abroad were screened at KIFF this year and the preparations have already begun for a bigger show next year in terms of quality of films representing different regions.