Members of a Mapuche Indian community in western Argentina are occupying a gas-processing plant owned by U.S. energy firm Apache, the company said Thursday.

The members of the Gelay Ko community began occupying Apache's plant outside the city of Zapala on Tuesday to demand an end to natural gas drilling, saying it is polluting water supplies in that area of Neuquen province.

They also want the provincial government to help them build homes and provide them with farm equipment, spokespersons for that indigenous community told the local press.

Apache, a Houston-based energy company that began operating in Argentina in 2001 but has been forced to halt drilling for security reasons, has urged the courts to intervene and resolve the conflict, company spokespersons told Efe.

The gas-processing plant, which supplies both residential and industrial customers and is located 1,600 kilometers (995 miles) southwest of Buenos Aires, near the Chilean border, has been surrounded by police to prevent disturbances.

The conflict also has caused a 30 percent drop in output at the plant, they added.

"We're remaining firm here. The blame lies with the province (Neuquen), which grants concessions without the permission of the communities that live in the area," Mapuche spokesman Martin Maliqueo told Argentine daily Rio Negro.

The Gelay Ko community accuses Apache of polluting potable water sources with its gas drilling and says the Neuquen government is ignoring its demands, including its request for social assistance.

Apache also holds concessions to oil and gas blocks in the southern provinces of Rio Negro and Tierra del Fuego and the western province of Mendoza, all of which are located near the border with Chile, where the bulk of the Mapuche population lives.