By DIANA JEAN SCHEMO

          RIO DE JANEIRO, Brazil -- As the Colombian government prepared for peace talks with
          rebels to try to end three decades of civil violence, an explosion believed to be the work of
          rebels hit the country's most important oil pipeline early Sunday, killing at least 25 people and
          wounding scores more.

          Police officials attributed the attack, on the Ocensa pipeline in northern Antioquia province, to the
          National Liberation Army, the country's second-largest rebel group. Its leaders were given a
          furlough from prison just a week ago to open peace talks with business and civic leaders.

          British Petroleum and the Colombian state oil company Ecopetrol are majority owners of the
          pipeline, which exploded shortly after 2 a.m. near the village of Machuca. The blast set fire to the
          village, where most of those killed were sleeping. Throughout the day, rescue workers flew to the
          region in helicopters to collect the dead and wounded.

          "We have reports of 25 dead and 65 injured," Guillermo Leon Franco, director of the Antioquia
          health department, told Reuters news service.

          The pipeline carries 350,000 barrels a day of crude oil from Colombia's largest oil operation, British
          Petroleum's Cusiana-Cupiagua complex, and the explosion froze pipeline operations. The attack
          occurred near the town of Segovia, in a region where right-wing paramilitary groups have grown in
          tandem with a heightened army presence to protect oil operations from rebel activity. Alfredo
          Rangel, a former national security adviser to the government, said the attack seemed to be a sign
          from the rebels that "they still have a presence in the region."

          Pipeline attacks have been a frequent source of income for the rebel group, which collects
          kickbacks from contractors hired to repair the damage. Several leaders of the Oil Workers Union
          are facing criminal charges for colluding in pipeline bombings.

          But until now, the main target of such attacks had been the Cano-Limon-Covenas pipeline, run by
          Occidental Petroleum. The rebels bombed the that pipeline 61 times this year and 64 times last year.

          Last year, 30 soldiers were killed and more than 15 wounded during guerrilla attacks on
          Occidental's pipeline and installations. Recently, attacks on the wellheads have become more
          frequent, a sign of the growing boldness of the rebels.

          By Sunday night, however, the rebel group had not come forward to claim responsibility. A
          commander of the group said through intermediaries that he could not reach the leaders at the front
          for confirmation, but he believed that members of his organization had carried out the attack.

          Like other oil companies working in Colombia, British Petroleum pays the government for military
          protection. Two years ago, the company acknowledged paying $33 million for a three-year
          protection contract. But the company has come under attack for alleged excesses by the army units.

          A newspaper investigation published over the weekend in The Guardian in Britain and El
          Espectador in Bogota said a British Petroleum security chief had helped arm and finance an army
          brigade implicated in death squad massacres in the 1980s. The man was dismissed after questions
          were raised, and the company has declined to comment.

          In recent days, the country's new president, Andres Pastrana, has given recognition as political
          movements to the National Liberation Army, believed to have 5,000 members under arms, and to
          the larger rebel group, the Revolutionary Armed Forces of Colombia, with an estimated 15,000
          combatants.