(Reuters) - Colombia's FARC guerrillas have vowed to continue capturing security forces while the government on Wednesday asked rebels to make it clear they are not wasting time at peace talks in Cuba and genuinely want to end the five-decade conflict.

President Juan Manuel Santos' government and Marxist guerrillas have been locked in peace negotiations in Cuba since November to try to reach a negotiated settlement to a war that has defied all past attempts for resolution.

The discussions are set to resume on Thursday.

The Revolutionary Armed Forces of Colombia, the biggest and oldest armed group in Latin America, seized two police patrolmen in a southwestern province last weekend - the first kidnapping of security forces since the group said last year it would stop taking hostages to finance its activities.

The FARC never said it would stop taking members of the armed forces as "prisoners of war" but in April of last year it released all government forces under its control.

"We reserve the right to capture members of the security forces as prisoners if they surrender in combat," the FARC said in a statement issued late on Tuesday in Cuba.

An escalation of hostilities could affect the progress of the peace talks in Cuba. Santos has said he wants to achieve an agreement within a year.

The chief government negotiator, Humberto de la Calle, said the Andean country would not be put off course by the recent kidnappings.

"We're going to Havana to end the conflict, that is what we agreed. And if it's not like that, they should tell us at once, so as not to waste the time of the government nor the Colombians," de la Calle said before returning to Cuba after a short break in talks.

"We will not be diverted from our goal nor we will be pressured into a ceasefire," de la Calle added.

At the start of talks in November, the FARC declared a two-month unilateral ceasefire, which ended on January 20 with the rebels attacking oil and mining facilities, including two pipelines and a coal rail line.

The government has refused to lay down its arms saying the ceasefire was a sham by the FARC to gain international attention. The army kept attacking the rebel group and carried out several aerial raids that killed at least 34 rebels.

Over its history, the FARC has held dozens of politicians, police officers and soldiers, while hundreds of its rebels are in Colombian prisons.

"We have told the government on several occasions that an exchange of prisoners should take place, but their reply was negative," the FARC said.

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 infrastructure, helping attract billions of dollars in foreign investment.

Santos is responsible for some of the harshest blows against the FARC, first as defense minister and then as president, including killing the group's leader Alfonso Cano in 2011.

The negotiations are the biggest gamble of Santos' career, and their success or failure could help determine who wins the next presidential election in 2014.

(Reporting by Luis Jaime Acosta; Writing by Eduardo Garcia; Editing by Will Dunham)

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