Militant Colombian Indians have seized an area they claim as ancestral homelands to prevent a U.S. multinational from drilling for oil and pledged yesterday to "defend Mother Earth to the death". Some 200 U'wa Indians occupied late Tuesday the Gibraltar-1 test site in the Samore block in northeast Colombia. The 500,000 acre (209,000 hectare) exploration area is tipped to harbour up to 2.5 billion barrels of crude and could ensure the country's energy needs well into the next century.Occidental Petroleum Corp won approval in late September to begin drilling for crude there after a seven-year legal wrangle over indigenous land rights blocked work.