BY FRANCES ROBLES

                      BOGOTA - In the two weeks since the government broke off peace talks with Marxist guerrillas, the
                      rebels have launched sweeping attacks against the country's infrastructure, disrupting electrical,
                      telephone and water service to tens of thousands of Colombians.

                      The offensive has proven more difficult to combat than the usual hit-and-run attacks on isolated
                      military or civilian government targets, raising the question of how the Colombian military can thwart
                      well-equipped guerrillas who avoid direct military engagements in favor of plunging large parts of the
                      country into darkness.

                      ''The characteristics of their attacks are changing. They used to target urban centers, small towns --
                      now they are leaving entire regions without service,'' said electric company spokesman Gabriel Gallón.

                      Since the war escalated Feb. 20, 56 cities across four departments have been left without power for
                      varying periods of time after strikes against 20 electrical towers and two substations. So far this year,
                      rebels have attacked 143 electrical towers, or more than half as many as the 254 attacks recorded
                      during the preceding 12 months. Repairs will cost a minimum of $10 million, government officials said.

                      Telephone service was interrupted for 147 cities and towns after rebels knocked out eight
                      telecommunications towers. The telephone company estimates it will cost $20 million to repair.

                      Two water aqueducts were hit, although not badly damaged, the government said. By Tuesday, much
                      of the country's telephone and electrical service had been restored.

                      According to Gallón, there are 20,000 potential electrical targets, posing a significant challenge for
                      military planners trying to stop the attacks.

                      Some combat has been reported, including the deaths of soldiers killed by FARC booby traps. At least
                      100 FARC guerrillas have been captured, the military said.

                      A FARC communiqué issued Monday claimed the rebels killed 84 right-wing paramilitaries. In a
                      statement released last week, FARC commanders defended the strikes against civilian targets, saying
                      the Colombian military engages in similar warfare.

                      ''They have thrown hundreds of bombs, each with 250 to 500 kilos of explosives that caused forest
                      fires, destroyed roads, bridges, community centers, peasant homes and the murders of three civilians,
                      including two children,'' the statement said.

                      Experts say the FARC offensive is tougher to beat because it takes just a handful of guerrillas to
                      launch an assault on an electrical tower. It would be impractical for the 150,000-member armed forces
                      to protect them all, experts said.

                      Col. Joseph Nuñez of the U.S. Army War College said the military has to pressure FARC's funding
                      sources and limit its ability to move about in the former demilitarized zone.

                      ''It's too simple to say the military cannot live up to the task,'' Nuñez said, stressing that the territory is
                      too huge for the military to handle alone. ``This will not be a war won on the battlefield.''