BOGOTA, COLOMBIA, SEPT. 6 -- President Cesar Gaviria has offered cocaine traffickers who turn themselves in and confess their crimes reduced prison sentences and a chance to avoid extradition to the United States.

The heart of Gaviria's election campaign was his pledge never to negotiate with drug traffickers, and today Gaviria and his top aides stressed that the government's offer does not constitute negotiations nor a retreat from extraditing traffickers who are captured. They pointed out that the first three extraditions of Gaviria's month-old presidency took place today.

Extradition has been a cornerstone of U.S. anti-narcotics policy because the Colombian judicial system is viewed as subject to intimidation and corruption by traffickers.

Anti-extradition sentiment surged here last month when D.C. Mayor Marion Barry was convicted of only one of 14 drug-related charges. The verdict outraged Colombians, who feel they are paying a high price to interdict the drug while consumption in the United States goes virtually unpunished, and the minister of justice said the outcome of the Barry trial would make it much more difficult to continue extradition.

Senior government officials today described the government's move as an effort to defuse public opposition to extradition and isolate top traffickers.

In a nationally televised address Wednesday night, Gaviria said traffickers who turn themselves in and "confess their crimes, give up their weapons and other possessions that are related to their crimes" would not be extradited to the United States.

"If they have committed crimes under narcotics or anti-terrorism statutes, their . . . confession to the judge will mean a reduction of their sentence by one-third," Gaviria said. "If they cooperate to discover new participants in crimes . . . their sentences can be reduced by as much as one-half."

Because the maximum prison sentence under Colombian law is 30 years, senior officials said that if Medellin cocaine cartel leader Pablo Escobar turned himself in and complied with the decreee, he could face a term of only 15 years.

The measures also apply to paramilitary groups that operate in rural areas, often in collaboration with drug traffickers, and that are believed by officials to be responsible for killing hundreds of people in recent years.

Leaders of the Medellin cartel, who call themselves "The Extraditables," have said repeatedly that they would surrender if they were tried in Colombia.

The Extraditables declared a unilateral truce on July 27, and since then have virtually halted their terrorist campaign, which claimed the lives of three presidential candidates, more than 200 policemen and hundreds of civilians.

"The Extraditables always used extradition for justifying their war," said a senior official. "This is a way out with justice being applied."

The Bush administration cautiously applauded Gaviria's move, although there was some concern that it could become a pretext for abandoning the country's war on the drug cartels.

"It has always been a goal of ours to seize these drug kingpins and bring them to justice," Attorney General Dick Thornburgh said in Washington. "If the government and people of Colombia are now able to enforce their own laws against drug trafficking -- prosecuting, convicting and incarcerating these thugs -- so much the better." However, Thornburgh cautioned that "if the so-called Extraditables fail to take advantage of this opportunity to surrender, confess their crimes and serve jail sentences, we will continue to support Colombia's effort to arrest and extradite them to the United States."

Gaviria said the government was acting from a position of strength, and was not "negotiating with any criminal organization."

Officials said today that they did not expect Escobar or other top leaders to turn themselves in but that they hoped the offer would spur lower and mid-level operatives to do so, damaging the ability of the drug cartels to operate.

"Realistically, we do not think Escobar or other capos will surrender," one top official said. "But it is the pyramid principle. You dig away at the base, and the top has to fall."

Gaviria said throughout his presidential campaign that extradition should not be the main tool in fighting drug traffickers.

"Today, no one can claim the government is acting under pressure because there is no intimidation, no bombing going on," one official said. "There has been no contact with the traffickers, not even public communiques by them. The time was right. It would be stupid to just continue extradition indiscriminately, but it would also be stupid to simply halt them."

Staff writer Michael Isikoff in Washington contributed to this report.