Environmentalists and activists for Brazil\'s indigenous peoples on Thursday cheered a federal court order halting construction at the controversial $11 billion Belo Monte hydroelectric dam. Government officials said meanwhile they would appeal the decision on the dam, a project which is a centerpiece of efforts to boost energy production in the rapidly growing economy but has drawn criticism both at home and abroad for its impact. Antonio Melo, spokesman for the Xingu Forever Alive movement, a coalition of dam opponents aimed at defending the river Xingu, hailed what he said was \"a partial victory.\" But he said he hopes the ruling is upheld, and that \"the justice system will fulfill its role and protect the population from the risk of losing its resources for water and food.\" The decision \"is welcomed by the indigenous communities threatened by the project,\" said Sarah Shenker, of Survival International, an advocacy group for tribal peoples. On the government side, the attorney general\'s office was \"not yet informed of the decision\" but \"will probably appeal,\" a source close to the office said. The court ruling Wednesday halted all work by the Norte Energia consortium, saying any alteration of the rive could cause irreparable harm to the environment. The decision was a major boost to environmentalists and Amazon Indian tribes who have decried what they say will be massive destruction of Brazilian fauna and flora in the area. The project has drawn international criticism, including from Oscar-winning movie director James Cameron of \"Avatar\" fame, who said rainforest indigenous tribes could turn to violence to block dam construction. The Belo Monte dam would be the third biggest dam in the world, after China\'s Three Gorges construction and the Itaipu dam on the border of Brazil and Paraguay. It would produce more than 11,000 megawatts, or about 11 percent of Brazil\'s current installed capacity. The project is expected to employ 20,000 people directly in construction, flood an area of 500 square kilometers (200 square miles) along the Xingu river and will displace 16,000 persons. The construction ban should be valid from the date that Norte Energia receives notification, likely next week, a federal justice spokesman said. The government had pledged to minimize the environmental and social impact of the dam and asserted that no traditional indigenous land was to be affected. But in April, the Inter-American Commission on Human Rights (IACHR) asked Brazil to \"immediately suspend the licensing process\" for the dam, and called on it to protect indigenous peoples in the Xingu River basin whose lives and \"physical integrity\" would be threatened. The dam would divert 80 percent of the Xingu River\'s flow to an artificial reservoir, \"potentially leading to the forced displacement of thousands of people,\" the Amazon Watch nonprofit, which fights for indigenous peoples\' rights and to protect the environment in the Amazon, says on its website. In June, the Brazilian government granted an installation license for the dam, clearing the way for construction to start.