More than 600 armed forces from Colombia have raided 63 illegal mines operated by the Revolutionary Armed Forces of Colombia (FARC) and arrested 59 people.
As part of the 'Operation Anostomus' near Colombia's border with Brazil and Venezuela in the Amazon, the armed forces raided mines that were used extract gold, tungsten and cobalt.
Colombia Defense Minister Juan Carlos Pinzon said that the operation undertaken by the army will deprive the guerrilla group of $9m per month.
Pinzon said by creating unlawful finances for illegal groups, such mining will destroy the environment.
For the group, mining of these minerals in addition to others illegally has become a major source of income.
Pinzon told media sources: "It is the cleanest and hardest blow in more than a decade, possibly one of the biggest in history, against illegal mining."
The troops arrived by air, land and along rivers to attack the mines in various locations in the east of Colombia.
The army extracted gold from riverbed sediment by destroying pumps and dredging equipment using explosives.
Among those arrested by the army were 12 alleged FARC guerrilla rebels, four from Brazil and one from Venezuela.
Reuters quoted a Colombian mining executive saying that tax-paying companies that are legally registered produce only about one-fifth of the roughly 57t produced by the country annually in sectors such as gold.