Officials say the FARC guerrilla group earns $2.4 billion-$3.5 billion a year abetting and aiding the drug cartels' trafficking of narcotics across the Americas with help from 8,147 members.
"Of the 350 tons of cocaine produced in Colombia, 200 are linked to FARC," Defense Minister Juan Carlos Pinzon said during a Colombia-U.S. forum address at the University of Miami.
He said the figures represented research by "multiple" intelligence sources.
Critics of the government, independent media and the United Nations have cited lower figures but acknowledge FARC earnings from organized crime and drug cartel links are high.
The number of FARC rebels cited by Pinzon, however, is lower than the highs reached in the late 1990s and 2000 when the group's ranks swelled to 20,000 men and women.
Although FARC is "a very different organization" now the rebel group isn't to be underestimated because of its capacity to adapt and change, Pinzon warned.
"FARC have mutated in their tactics and forms of attack against the Colombian armed forces with snipers and improvised explosive devices, as well as an increase in the attacks against energy infrastructure and renewed contacts with social movements," Pinzon said.
Santos announced this week a $5.7 billion increase to Colombia's 2013 defense budget, indicating the government will continue its pressure on rebel groups even as it prepares for the next round of peace talks in Cuba.
"Not for a single day or minute will we let our guard down against violent actors that threaten the life and work of the honest Colombian," Santos said in a message to the National Federation of Oil Palm Growers.
The increased funds will help maintain a government armed force of about 25,000 police and armed forces involved with the fight against militants and the drug trade. U.S. military experts said the Colombian operation at different levels.
Santos said the government's military strength put it in a better position to speak of peace. "We look forward to the end of the conflict in earnest, with dignity, prudently and without repeating past mistakes," he said in comments quoted by ColombiaReports.com website.
The peace talks have pitted Santos and his military command against major political and security challenges, the biggest of which is how to absorb the FARC fighters in Colombia's civilian life.
Still undecided are questions of amnesty and immunity from prosecution for FARC militants and protection from extradition to the United States of FARC activists wanted by U.S. authorities.