A former Colombian army captain has been arrested on suspicion of acting as the chief accountant of a major drug trafficking gang, prosecutors said Tuesday.

Johan Arenas Rua was arrested in the northwest department of Antioquia, prosecutors said in a statement.

An indigenous court convicted seven FARC guerrillas of murdering two leaders of the Nasa tribe in western Colombia on Sunday, sentencing them to between 40 and 60 years in jail and 20 lashes.

The harshest sentence -- 60 years prison time -- was handed down to Carlos Ivan Silva, who confessed to killing two native leaders on Wednesday. 

The European Union said Tuesday it is ready to provide "concrete assistance" to Colombia to help implement any peace accord it can reach with FARC rebels after years of bloody conflict.

Talks between the center-right government of President Jose Manuel Santos and the Marxist-inspired FARC have so far produced three tentative accords out of five outlined in an overall peace deal.

Colombian President Jose Manuel Santos on Monday began a whistlestop tour of Europe to drum up support for a possible peace deal with FARC rebels to end five decades of insurgency.

His visit to six European Union nations, starting in Spain, follows two years of peace talks in Cuba between the Marxist-inspired rebel group and Santos's center-right government.

Colombia said Friday that 12 miners trapped in a coal shaft are probably dead after the mine flooded with water.

The 12 men, aged between 23 and 55, became trapped Thursday in the mine in Amaga in northwestern Colombia when the pit filled with water.

The Colombian rebel group FARC acknowledged for the first time on Thursday its actions have affected civilians and said it is ready to take "responsibility."

The admission comes as FARC and the Colombian government are engaged in peace talks in Cuba to end the country's long-running conflict.

A former commander of Colombia's leftist FARC rebels was jailed for 27 years on Friday for his role in the 2003 kidnap of three U.S. citizens held captive for five years, the U.S. Justice Department said.

Alexander Beltran Herrera, 38, pleaded guilty in March to three counts of hostage-taking relating to the abduction of Marc Gonsalves, Thomas Howes and Keith Stansell.

Colombia's two top rebel groups, the ELN and the FARC, will hold separate peace talks with the government, the ELN said Monday, as the sides aim to end decades of conflict.

The National Liberation Army (ELN), said its negotiations will be held parallel to the ongoing talks between the government and the leftist Revolutionary Armed Forces of Colombia (FARC).

Twelve adults and five children suspected of child sex crimes and human trafficking have been arrested in Colombia in a joint operation with the United States, officials from both countries said Tuesday.

The suspects are accused of pimping, sex tourism, human trafficking and drug crimes, the Colombian prosecutor's office said in a statement. 

Lightning struck dead 11 Colombians and injured 15 others during a meeting of indigenous Wiwa spiritual leaders in a remote mountainous area in the country's north, the government said Monday.

The Wiwa, who were gathered at a community in the isolated Sierra Nevada de Santa Marta range in Magdalena department, were killed by "an electrical charge from a lightning bolt," the national ombudsman's office said.