Last week, the government granted the 7,000-member U'wa tribe a huge new reservation of some 543,000 acres (220,000 hectares) -- five times larger than their previous reserve -- in an oil-rich corner of northeast Colombia.

The move was aimed at resolving a seven-year land rights dispute that had forced Occidental Petroleum Corp to suspend the search for what was tipped to be one of Colombia's largest ever reserves, with between 1.5 billion and 2.5 billion barrels of crude.

Such a find would boost Colombia's oil output, currently stagnant at 850,000 barrels per day, and stave off the threat that the country would become a net crude importer by 2004. At present oil is Colombia's top legal export, bringing in some $2.5 billion in foreign earnings a year.

U'wa leaderssent a letter to President Andres Pastrana Tuesday thanking him for the enlarged reservation but insisting that their cultural and spiritual claim extended to a much larger area where their semi-nomadic ancestors used to roam. "Because of the principles that guide our cultural vision, the U'wa people are ready to fight to defend our territorial integrity," Evaristo Tegria, a member of the U'wa ruling council, told Reuters by phone from the town of Cubara in a remote northeast corner of central Boyaca province.

"The U'wa will not permit any oil exploration or production (on ancestral lands) either inside or outside the area that has been legally recognised as ours," he added.

The U'was live largely from farming maize, yucca, plantains and beans in the mountain cloud forests and plains of central Boyaca and northeastern Santander, Norte de Santander and Arauca provinces.

In 1992, Occidental was granted exploration rights to the 500,000 acre (209,000 hectare) Samore block, about half of which overlappedtwo natural parks and part of the U'wa reservation.

The U.S. Multinational spent about $12 million on seismic surveying before halting all operations in the face of U'wa threats to commit mass suicide if Occidental tried to drill for what the tribe views as "the lifeblood of Mother Earth".

The outcome of its application for a government permit to sink the first test drill, known as the Gibraltar 1 well and expected to cost some $30 million, is anticipated within the next two months. Occidental has so far made no official comment about the U'was vow to continue their opposition to its plans.