BOGOTA, COLOMBIA, JAN. 26 -- President Virgilio Barco vowed not to be blackmailed by cocaine barons who killed his chief prosecutor in the first salvo of a "total war" on efforts to extradite them to the United States.

The nation's largest newspapers voiced support for the president's pledge to bring to justice the billionaire smugglers whose bribes and private armies have allowed them to operate with near impunity.

An autopsy showed that Attorney General Carlos Mauro Hoyos Jimenez was killed yesterday about nine hours after his abduction in the drug center of Medellin. Twelve bullets were found in the body. His two bodyguards were killed in the ambush.

{Attorney General Edwin Meese III, in Washington, termed the killing "a tragedy for the citizens of Colombia who believe in the rule of law and hold the (Medellin drug) cartel in contempt." He offered help in bringing the perpetrators to account and added, "To those here in the United States who buy and use cocaine, I say this: the blood of Carlos Mauro Hoyos is on your hands, too."}

In a nationwide address last night, Barco said the government would not "surrender to vile blackmail and infamous threats." Drug traffickers "will not intimidate us," he said.

Barco's government, through Hoyos, said earlier this month that it intended to renew efforts to arrest and extradite Colombia's leading traffickers to face U.S. criminal charges. A group calling itself "Los Extraditables" said it killed Hoyos because he persisted in extradition efforts. On Sunday, the group declared "total war" on Hoyos' ilk.

The extraditions were suspended last year when the Supreme Court struck down as unconstitutional a 1979 extradition treaty on a technicality. The government now says either of two previous treaties will suffice.

The U.S. and Colombian governments were discussing a format for the extraditions before Hoyos was killed, a diplomatic source said. Fearing reprisals from drug traffickers, the source asked to remain anonymous.

Another diplomat said Barco had summoned the acting U.S. ambassador, Phillip McLean, to the presidential palace yesterday.

Hoyos, 49, was kidnaped near the Medellin airport by at least six men in four vehicles who sprayed his limousine with submachine-gun fire. His body was found near the airport, where Hoyos had been heading for a flight to Bogota, 200 miles to the southeast.

Colombia's largest daily newspaper, El Tiempo, said in its main editorial today that Colombians must give "unconditional support to the president." Another Bogota daily, El Espectador, proposed "a crusade for national salvation" in a front-page editorial. The paper's editor, Guillermo Cano, was murdered by traffickers in December 1986.

In a bloody four-year campaign against efforts to bring traffickers to justice, they have killed another newspaper editor, a justice minister, 21 judges and scores of policemen and soldiers, the government notes.

In addition to the threat of assassinations, Barco must deal with corruption if he expects to beat the traffickers. Newspapers frequently have reported on drug money financing the campaigns of elected officials.