Survival International urged Brazil to end impunity for those behind the murders of indigenous people as it highlighted the arrest of 18 suspects in the high-profile killing of a Guarani Indian chief. Survival International, a leading advocate for tribal peoples\' rights, hailed as a \"positive step\" the 18 arrests in connection with the killing of chief Nisio Gomes in the western state of Mato Grosso do Sul last November. Authorities said at the time that 42 heavily armed, hooded men attacked the Kaiowa Guarani community in the village of Amambai, near the border with Paraguay, and shot 59-year-old Gomes. The assailants kidnapped a child and two youths and took away Gomes\' body, which has never been found. \"Brazil should remember that Nisio (Gomes) isn\'t the only indigenous activist to be murdered in cold blood,\" Survival\'s Director Stephen Corry said. \"For years, powerful landowners have hired hit-men to kill those that challenge them. The culture of impunity must end if this situation is to change.\" In a statement, Survival said that among the suspects taken into custody was \"the owner of a notorious security firm which hires out gunmen to patrol areas of land occupied by ranchers.\" Federal police have also linked other prominent suspects to Gomes\'s murder, including six ranchers, a lawyer and a civil servant, it added. \"Brazil\'s Guarani are repeatedly thrown off their land by cattle ranchers and forced to live in dangerous conditions by the roadside or in overcrowded reserves,\" the rights group said. The violence is linked to land disputes in a country where one percent of the population controls 46 percent of the cultivated land. Guarani Indians have been trying to recover a small portion of their original territories, but face violent resistance from wealthy ranchers as well as soya and sugar cane plantation owners.