* Santos defends Uribe against rebel criticism
* Escalation of violence proves FARC not spent
* Tense week of peace negotiations in Cuba
Colombia's FARC rebels on Saturday admitted to holding two police patrolmen and a soldier it seized last week and pledged to free them in an apparent goodwill gesture at the end of a tense week of peace negotiations with the government.
The captured soldier had not previously been announced by the Defense Ministry.
The Revolutionary Armed Forces of Colombia, the biggest armed group in Latin America, said in a statement it would release the three security officials to the International Committee of the Red Cross and a local peace group.
"We communicate to the families that they are in good health and receiving respectful and dignified treatment," said the statement, dated Feb. 1. "It doesn't cease to surprise us that the defense ministry remained silent" about the soldier.
The announcement comes after a difficult week of peace negotiations in Cuba as the two sides traded barbs amid an increase of violence, kidnappings and attacks on economic infrastructure.
For more than a decade, U.S.-backed strikes against the FARC have severely weakened the rebels and limited their ability to attack the country's economic drivers, helping attract billions of dollars in foreign investment.
But the escalation of violence in recent weeks has left scores of insurgents and government troops dead, demonstrating that even while the FARC is weakened, it is by no means dead.
The government has demanded the FARC stop its practice of kidnapping while the guerrillas this week made clear it would continue to capture members of the armed forces which it regards as "prisoners of war."
President Juan Manuel Santos took the biggest gamble of his political career and faced pressure from opposition leaders when he started talks with the FARC. Attempts by previous governments to end the conflict have ended in shambles and helped energize the rebels and intensify fighting.
The FARC, as the drug-funded group is known, vowed last year to abandon kidnapping for ransom, but this week it seized and later freed three oil workers.
Over its history, the FARC has held dozens of police officers, soldiers and politicians hostage, including French-Colombian presidential candidate Ingrid Betancourt, seized in 2002, and three Americans taken a year later.
Betancourt and the U.S.-defense contractors were rescued by the military in 2008, when Santos was defense minister.
In a separate statement on Saturday, the FARC - which began in 1964 as a Marxist agrarian group fighting social inequality - accused former President Alvaro Uribe of trying to ruin the peace talks. It also said he had ties to right-wing paramilitary groups and drug traffickers.
Uribe, who battered the group for two straight terms and is credited with bringing it close to defeat, has been a loud critic of the talks, accusing Santos of seeking a name in the history books above all else.
Santos, despite being at the sharp end of Uribe's criticism, called on the FARC to respect his predecessor.
"The national government rejects the communique issued today by the FARC in Havana and demands respect to the dignity of ex-President Alvaro Uribe," the president's office said.
"The negotiation table is aimed at seeking an end to the conflict so such declarations in no way contribute to that end."