An indigenous leader who for decades fought for his people's right to live on their ancestral lands, was murdered in Brazil's Mato Grosso do Sul state, police said. Ambrosio Vilhalva, a Guarani tribal elder, was stabbed to death on Sunday at the entrance of his community known as Guyra Roka, according to press reports and London-based group Survival International, which champions the rights of indigenous people worldwide. Brazilian federal police confirmed his death on Tuesday but gave no further details. Vilhalva was found dead in his hut, with multiple knife wounds, Survival said, adding that the tribal chief had been repeatedly threatened in recent months. A news website in the area quoted local civilian police as saying the Guarani leader was killed by his father-in-law as a result of a family dispute. "The story is full of contradictions and the case is under investigation," the website, Dourados Informa, quoted police inspector Benjamin Lax as saying. Survival said that Vilhalva had starred as the main character in the award-winning film Birdwatchers , which portrays the Guarani tribe's desperate struggle for their land. Guarani Indians, whose total population in Brazil is estimated at 46,000, have been trying to recover a small portion of their original territories, but face violent resistance from wealthy farmers as well as soya and sugar cane plantation owners.