The spill affected the Urubamba river some 400 kilometers (250 miles) east of Lima in the province of Cusco, the Ministry of Energy and Mines said in a statement.

The statement did not say how much of the highly volatile liquid spilled, but did say that half of it "evaporated immediately." The remainder reached the Urubamba river "and dispersed immediately."

Environmental and advocates for indigenous people have long argued the Camisea project would harm Peru's Amazon rainforest and native communities.

The company that operates the pipeline studied the area of the spill and nearby rivers, and determined that "without having detected any effect" on the fish and animals in the region.

However Francisco Panera, a Catholic priest whose parish includes Camisea, said he found hundreds of dead fish and scores of families affected by the spill.

Camisea, a 1.6 billion dollar venture led by Argentina's Pluspetrol and Techint and US-based Hunt Oil Co., aims to bring gas from deposits in southern Peru to Lima and a marine terminal and to turn Peru into an energy exporter.

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