LA PAZ, BOLIVIA — COLOMBIAN traffickers have set their sights on Bolivia: Dozens of Colombian drug traffickers, some heavily armed, are moving into remote jungle towns in northern Bolivia to take control of the local cocaine business, the United States Drug Enforcement Administration (DEA) says.Bolivian anti-drug police late last month destroyed what they describe as the largest cocaine laboratory ever found in the country, which officials say probably belonged to traffickers based in the Colombian city of Cali. The laboratory, situated in the jungle areas of the Beni, Bolivia's subtropical region where most of the country's cocaine laboratories are found, was capable of producing five tons of cocaine a week. DEA officials say that from the evidence of the tire marks left on the airstrip near the laboratory, small planes known as Airocommanders probably flew the cocaine up to 1,000 kilometers (625 miles) into Colombia. The types of arms and the frequencies of radio transmitters left at the site strongly suggest links with Cali, drug officials say. As many as 300 Colombians, most with connections in Cali, are attempting to fill the void left by the recent surrender of seven top suspected Bolivian cocaine smugglers, DEA sources say. The seven took advantage of a government amnesty which granted traffickers a two-day period to give themselves up in return for guarantees they would not be extradited. The offer expired in November. "Every day the seven stay in custody, they lose that much more power," says Don Ferrarone, DEA chief in Bolivia. "They left their people in place, but they are being bypassed by the Colombians." DEA intelligence sources say Colombian traffickers are fighting it out like the old Wild West in some remote towns of the Beni. Whole organizations - including bodyguards, managers, and chemists - are trying to get laboratories back in action and reestablish air routes hit by recent anti-drug raids, they say. In June, a huge DEA-orchestrated anti-drug operation named "Safe Haven the largest ever of its kind in Bolivia - sought to take over Santa Ana, the hub of cocaine business in the Beni. "Safe Haven" failed to capture three of the DEA's targeted traffickers living in Santa Ana: Erwin Guzman, Hugo Rivero, and Oscar Roca. But the operation was thought to have prompted the three to turn themselves in. Interior Minister Carlos Bruno Saavedra, the architect of the amnesty, has scored a major political success, analysts say. But he admits "it is too early to say" whether the surrender of the seven has made a dent in Bolivia's $400 million a year cocaine trade. Mr. Saavedra says the impact will depend on "what sort of information the seven give, and what sort of sentences they receive." Despite the surrender of alleged drug lords, the Bolivian government may lose one third of $66 million in US balance-of-payments support for 1991. The money is dependent on Bolivia eradicating 7,000 hectares of coca before the end of the year. So far, only around 4,500 hectares have been destroyed. The US embassy says it is concerned that the seven could still secretly run their operations from their prison cells. A plane belonging to one of the seven, Winston Rodriguez, was reported in the local press to have been found ferrying coca paste in Peru's Upper Huallaga Valley, the world's largest coca-growing area. The DEA is convinced most of the seven are not revealing anything new or important about their operations. "Only a fraction of them are giving us information," says Mr. Ferrarone of the DEA. Mr. Guzman, the first of the seven to surrender, is regarded by the DEA as the "godfather of them all, and the country's No. 1 trafficker." In his preliminary statement to a judge, Guzman denied he was directly involved in cocaine smuggling, but admitted he had financed the operations of other traffickers. The DEA is not convinced. "We are going to stay on this guy until he pays his debt to society," warns Ferrarone. "He's just not going to get away with it." Guzman and several others who appear on a list of so-called "extraditables" wanted in the US can expect a 10- to 15-year sentence. The US ambassador to Bolivia, Richard Bowers, caused nationalist heckles to rise when he recently announced the US government was not going to forego its "right" to seek the extradition of top traffickers. Some analysts say Mr. Bowers' comments discouraged other smugglers from giving themselves in. "Traffickers who hand themselves in will never be extradited," came Saavedra's sharp rebuff. Most Bolivians support the decree, and opposition politicians and the Roman Catholic church have called for its extension. A number of major Bolivian traffickers still at large have not surrendered. In the last few years, Bolivian organizations have engineered a certain degree of independence from the Colombians, particularly by opening up new routes via Brazil, Argentina, and Paraguay to Europe and Japan. But they are now losing out to the Colombians, the DEA says."The Bolivians are now getting blown aside," says Ferrarone.