BOGOTA, COLOMBIA, NOV. 3 -- A new offer by Colombia's most violent drug traffickers to surrender in exchange for amnesty and a halt to extradition is aimed at achieving their goals through constitutional reform, not direct talks with the government, sources close to the traffickers and officials say.

The proposal was contained in a letter, made public Friday, from a lawyer representing the traffickers. The letter was addressed to a group of prominent citizens seeking to negotiate the freedom of seven kidnapped journalists. The group is also expected to exercise considerable influence in a forthcoming convention to rewrite the nation's constitution.

While the "Extraditables," as the traffickers call themselves, have offered to surrender under similar conditions in the past, most recently in January, the government has refused to negotiate with them.

Sources familiar with the thinking of the Extraditables say the traffickers believe the constitutional assembly represents a unique chance to achieve their goals of an amnesty and an end to extradition by allying themselves with delegates elected to the assembly and bypassing the government.

Those elected to the 70-seat body on Dec. 9 will begin meeting next February and are to produce a final document six months later. They will have unlimited power to change the constitution.

The sources close to the traffickers said the kidnapped journalists were being held as a "life insurance policy" for leaders of the powerful Medellin drug cartel, and that the most prominent ones, at least, would not be released until the constitutional reforms were enacted. The notables who have been seeking the release of the journalists head political movements that are likely to be well-represented in the convention.

"What we will see is a great civil war in the assembly between the forces of the narco-traffickers and those opposed to {them}," said one political observer close to President Cesar Gaviria. The convention "is not meant to revolve around drug trafficking, but that is how it will end up."

In January the Extraditables offered to halt drug production and turn themselves and their goods over to Colombian authorities provided they would not be extradited to the United States to stand trial. The government did not respond to the offer.

Even proponents of extradition say it will almost certainly be made unconstitutional because it is widely disliked on nationalistic grounds. The United States has said repeatedly that extradition is essential to combating the traffickers because dozens of Colombian judges have been killed by the cocaine cartels and others have been intimidated or corrupted.

For the past 15 months extradition has been carried out by executive order under state-of-siege laws. On Sept. 5, Gaviria announced that any traffickers who turned themselves in and confessed to their crimes would be tried in Colombia, but the decree apparently not have gone far enough to satisfy public opinion or the traffickers.

"They are going to ban extradition, we know that," said a senior Gaviria adviser. "The real war will be over a pardon or political treatment for the traffickers."

Gaviria, who took office Aug. 7, campaigned in favor of the assembly as a way of reforming the judicial system and modernizing the Colombian state.

Pablo Escobar, leader of the Medellin cartel, already is working to help elect those he feels favor his proposals. When Escobar's cousin Hernando Gaviria was killed by police on Oct. 23, police found two handwritten letters from Escobar urging support for former Medellin mayor Juan Gomez Martinez, who is running for the assembly and who has long been a proponent of dialogue between the traffickers and the government.