By Nelson Acosta and Sarah Marsh
HAVANA (Reuters) - A leader of Colombia's FARC rebel group said on Thursday it was investigating why a breakaway unit is opposing a potential peace deal with the government that would end five decades of war.
The Armando Rios First Front, a 200-strong FARC guerrilla unit in Colombia's southeastern jungle province of Guaviare, said in a statement on Wednesday that it will not lay down arms or demobilize under a peace accord.
The statement raised fears that other units could also reject an agreement, throwing the peace process into doubt.
Revolutionary Armed Forces of Colombia (FARC) commander Pastor Alape said the group's leadership was still looking into the reasons behind the statement from First Front, which once gained notoriety for holding ex-presidential candidate Ingrid Betancourt and three American contractors hostage.
But Alape told Reuters the leadership was confident of unity within rebel ranks, despite the one public sign of discord.
"We need to talk with the people, see what the problem is and what the real intentions are," Alape, 57, told Reuters. "The other fronts are supporting the line (of peace)."
The FARC and Colombia government have been in negotiations in Cuba for almost four years and announced last month that they tantalizingly close to an agreement that would end Latin America's longest-running civil conflict.
President Juan Manuel Santos said on Wednesday that any FARC unit that did not adhere to a peace agreement would continue at war and be killed or jailed. The Marxist group has an estimated 7,000 fighters scattered throughout the country.
The FARC, which formed as an agrarian movement in 1964, and the government signed a landmark ceasefire deal two weeks ago, to come into effect when a peace deal had been reached and approved by Colombians in a referendum.
Santos, who has staked his legacy on ending a war that has killed hundreds of thousands and displaced millions, has said the two sides would aim to reach a final deal by July 20.
Alape said meeting that deadline was "impossible," however.
"The president can say many things but the reality of the country indicates something else, starting with the fact the government (negotiators) aren't even in Havana at the moment, because we said we would work each on our own side," said Alape.
"We wouldn't be capable (of reaching a deal) by the 20th, we would collapse, we'd have to work 94 hours in a row."
The two sides are hammering out the final details of general accords already reached and working on the minutiae of a truth commission and special tribunals that would try former combatants.
"There is still a lot of work," Alape said.
(Editing by Helen Murphy and Tom Brown)