COLOMBIA'S PACIFIC JUNGLE - Amid stifling heat and humidity in the remote Colombian jungle, guerrillas carrying machine guns and rifles creep their way through the undergrowth, patrolling along a river where their presence assures control over important transport routes for the cocaine they tax.

The Segunda Marquetalia group was formed in 2019 by dissident members of the now-demobilized Revolutionary Armed Forces of Colombia (FARC). They say the government has failed to comply with the terms of a 2016 peace deal that ended the FARC's part in Colombia's long conflict - and they want more concessions before they will give up their guns.

Segunda Marquetalia remains loyal to the Marxist ideals, like land redistribution, that inspired the FARC's 1964 founding, and many Segunda Marquetalia leaders are long-time FARC veterans now in their 60s.

Some fighters at a camp visited by Reuters - the first time the group has allowed any media organization to visit one of its camps - still sport symbols, like a wristband with an image of Che Guevara, long associated with Latin American rebel groups.

But times have changed in other ways. Many of the rank and file, some still just adolescents, own cellphones. A generator at the camp in southwestern Colombia powers a satellite internet link that allows them to video call their families.

The 1,700-member Segunda Marquetalia are one of a handful of remaining rebel groups holding talks with Colombia's first leftist president, Gustavo Petro, who has been trying to firm up new peace deals before his term ends in 2026.

Although those talks in general have been faltering, the government has expressed optimism that a deal with Segunda Marquetalia could be possible, and with it an end to the group's part in the six decades of armed conflict that have killed at least 450,000 people.

However, Segunda Marquetalia's chief negotiator told Reuters that the rebels want to see significant progress on social investment before they will discuss handing over their weapons - one of the government's central demands.

"That's what we'd like, to reach agreements and sign a peace deal," said head negotiator Walter Mendoza, whose legal name is Jose Vicente Lesmes, at an interview in a wooden, tin-roofed village house several hours from the camp. "But two years is very little, and the opposition to Petro's government is tremendous."

Mendoza, who at 67 is a four-decade rebel veteran, said investment in long-neglected parts of the country is a priority for the guerrillas before they will surrender the leverage offered by arms.

"Right now neither arms nor demobilization are on the table at talks," said Mendoza, clad in a keffiyeh scarf and camouflage pants. He said they first want to see construction of roads, schools, and clinics, and electricity provision in Colombia's remotest regions. "First things first - transformations of (rural) areas, concrete steps."

"The immovable lines are: no demobilization or handing over weapons beforehand," Mendoza said.

RECRUITING YOUNGSTERS

Mendoza instructed a group of guerrillas to show Reuters journalists a Segunda Marquetalia camp. The journalists traveled four hours by motorized canoe, a four-wheel vehicle and on foot to reach it.

The rebels explained that an extensive supply network brings food and gasoline into the camp via boats or vehicles. Fighters mostly eat staples like rice, potatoes, pasta, beef and chicken.

The nearest rural community is deeply poor. Some residents grow coca, the base ingredient in cocaine, as well as subsistence crops like bananas. Signs on ramshackle buildings celebrate the rebels.

At a makeshift parade ground, some 50 rebels returning from patrol stood to attention in their military gear, carrying M16 and AK-47 rifles.

Although many of the rebels are grizzled veterans, some fighters are as young as 16.

Colombia's rebel groups and crime gangs regularly forcibly recruit young people - including some women - or attract them with promises of economic opportunities or political struggle, in a bid to control swathes of territory crucial to drug trafficking and illegal gold mining, which security sources say are armed groups' top sources of financing.

Mendoza denied the group was directly connected to drug trafficking but acknowledged it taxes narcotics profits in areas under its control.

The Segunda Marquetalia has avoided direct battles with the armed forces since its founding, but has fought other armed groups for territory and control of illegal industries, the government says.

Mendoza also acknowledged that Segunda Marquetalia has a presence in Venezuela, "a buffer zone" he said gives commanders space to deal with political, logistical and financial issues.

Colombian officials have frequently accused guerrillas of evading military offensives by taking refuge in Venezuela with the permission of President Nicolas Maduro, something Caracas denies.

END TO ARMS

Armando Novoa, the government's chief negotiator at the Segunda Marquetalia talks, told Reuters two years would be enough time to agree and implement a deal with the group.

But he acknowledged there remained "enormous difficulties and obstacles," saying the surrendering of the group's weapons was a key element of the negotiation for the government.

"I don't know if it's a red line or not, but of course for us it's a central aspect of the negotiation," he said.

The government agrees on the need to fight poverty and invest in healthcare and education, Novoa said, but that development requires "an end to the violence of illegal arms."

Eduardo Pizarro, a former ambassador and victims' representative at the FARC talks, said the group refusing to give up their arms "kills the possibility of a successful peace negotiation."

"Holding on to weapons is absolutely untenable, it totally poisons the credibility of the process," he said.

The government's efforts with other armed groups have sputtered.

A six-month ceasefire with the larger National Liberation Army (ELN) guerrillas recently expired and the ELN has repeatedly warned negotiations are in crisis.

Discussions with the Estado Mayor Central, another dissident FARC faction, are taking place with less than half that group's original units, while the Clan del Golfo crime gang initially rejected surrender negotiations, though the government this month authorized tentative conversations.

A victory by a right-wing candidate in Colombia's 2026 election could fuel the conflict, Mendoza said.

"The guerrillas are not going to disappear," Mendoza said. "As long as the people support us, the armed struggle will continue."

In the Segunda Marquetalia camp, Ernesto Rojas said he had been a rebel fighter for more than a decade, first with the FARC and then with Segunda Marquetalia, where he is now a commander of the Jacobo Arenas unit. He said a peace agreement would not happen overnight, but could be reached.

"We'll always be open to a political solution to the conflict, whether with this government or the next, as long as the state is also open to it," Rojas said, as he propped a rifle between his legs.

  - Reuters