BOGOTA (Reuters) - Soldiers killed the security chief of the top commander of Colombia's FARC guerrillas in a gain for the government in its war on a decades-old leftist insurgency, authorities said on Saturday.
Alirio Rojas, known as the "Grandfather," died in a clash with the army on Friday, three months after troops killed the previous head of security for FARC commander in chief Alfonso Cano.
Rojas died in Tolima, an emblematic region for the guerrillas where they first began fighting in 1964, just 150 miles southwest of the capital Bogota.
President Juan Manuel Santos, who is seeking to pacify rural Colombia while keeping up an offensive on rebel enclaves, congratulated the army for an "important blow" against the Revolutionary Armed Forces of Colombia.
"We are hitting the FARC central command systematically," he said. "Ringleader that they name, ringleader that we kill."
Colombia is still battling armed groups and powerful new criminal gangs funded by the cocaine trade, but improved security has seen billions of dollars in investment pour into the country, mainly in oil and mining.
Santos took office in August and has kept up predecessor president Alvaro Uribe's crackdown against left-wing rebels, paramilitary gangs and drug traffickers. Santos scored an early political and military victory last year with a raid that killed a top FARC commander.
On Monday, his government rejected a prisoners exchange with the FARC, whose forces have dwindled to less than 8,000.
Santos next weekend will sign a law to redress abuses from the armed conflict and return land seized from peasants. He says the law will turn the page on decades of bloodshed and bring peace and prosperity to the countryside.
Santos has also patched up ties with his leftist neighbor President Hugo Chavez, who is moving to deny Colombian rebels a safe haven in Venezuela, where authorities have captured and deported to Colombia several guerrillas this year.
(Reporting by Anthony Boadle; Editing by Vicki Allen)