Colombian President Alvaro Uribe last night accused leftist rebels of murdering 11 kidnapped legislators last week.
The Revolutionary Armed Forces of Colombia, or Farc, said the 11 were killed in a gunfight when an unidentified military group attacked the camp on June 18th.
But Mr Uribe said government troops were nowhere near the area where the legislators were being held and called the Farc statement a ploy to cover up "this crime against humanity."
"No rescue mission was under way," Mr Uribe said. "They were deliberately assassinated."
"The most likely scenario is the camp was being attacked by an illegal paramilitary group and that the Farc executed the hostages," said Pablo Casas, an analyst with independent Bogota think tank Security & Democracy.
The 11 were captured along with another fellow provincial lawmaker in Valle del Cauca's capital city, Cali, in 2002.
Colombia was shocked when the Farc guerrillas kidnapped the lawmakers by masquerading as soldiers and calmly escorting them onto a bus, saying they were being evacuated due to a bomb scare.
The 12 were among about 60 high-profile hostages that the government wanted to swap for guerrillas held in government jails.
But Mr Uribe, whose father was killed by the guerrillas more than 20 years ago, said last week's crime reinforced his refusal to grant the Farc's demand for a safe-haven area to serve as a meeting place to negotiate a hostage swap.