The Colombian government and rebels from the leftist Revolutionary Armed Forces of Colombia (FARC) have exchanged blame over a peace process to resolve the decades-long conflict between the two sides.

President Juan Manuel Santos must make strong gestures to avoid another half-century of conflict in the South American nation, a commander for the FARC rebel group told the AFP news agency on Monday.

The statement was published by the agency after the government's top negotiator said on Sunday that the peace negotiations had hit a critical low point, with FARC stepping up violent attacks, and that the government could walk away from the process unless the group showed more commitment.

The government has taken part in Cuba-hosted talks with FARC since late 2012 to end the 50-year conflict.

Deals have been reached on most of the agenda, but the process is now under unprecedented strain.

'Important steps needed'

FARC commander Pastor Alape, who is a member of the negotiating team, told AFP that both sides needed to take important steps to "deepen the de-escalation of the armed conflict". 

"Today we need strong gestures ... to prove that President Santos will become the president of peace," said Alape, a senior figure in Colombia's main rebel group, which according to official figures still has nearly 8,000 fighters, mainly in rural areas.

On Sunday, government negotiator Humberto De la Calle said in an interview distributed to the press: "I want to tell the FARC in all seriousness, this could end.

"Someday, it is probable that they will not find us around the table in Havana."

However, Alape said he did not think the government was ready to quit negotiations, even with Santos under pressure from rightist parties.

"We prefer to think the president is committed to bringing this process forward and is the man who signs Colombia's peace deal to become the man who is known in history," Alape said.

The FARC unleashed a wave of bomb attacks on oil pipelines in recent weeks, rupturing those close to rivers and causing an environmental disaster that is expected to take two decades to clean up and has already reached the Pacific coastline.

Soldiers killed

Earlier optimism that had grown over the peace talks, boosted by the FARC's agreement to clear landmines, was shattered after the group ambushed and killed 11 soldiers in the southwest in April.

The attack led the government to resume air raids against FARC jungle bases, in turn prompting the rebels to abandon a unilateral ceasefire.

The FARC's insistence that the government agree to a bilateral ceasefire, even as its negotiators flatly reject the idea some members should serve jail time for the group's worst crimes, has dimmed prospects for a deal.

De la Calle said the government was prepared to consider a bilateral ceasefire before a deal is signed, if the FARC accepts judicial responsibility for the violence it has perpetrated and only if it also abstains from extortion and the drug trade.

In a conciliatory move on Friday, the FARC leadership in Havana said they were seeking to "de-escalate" the conflict after weeks of attacks in which several soldiers and police have been killed.

Analysts say the group's numbers are falling and all-out war is no longer seen as a realistic option.

Source: Agencies