From left, FARC members Jesus Santrich, Ivan Marquez (also known as Luciano Marin), and Ricardo Tellez attend a press conference in Hurdal on Oct. 18. Rebel commander Luciano Marin highlighted the obstacles that lie ahead for negotiations designed to end the Andean nation’s long war. (Audun Braastad/AFP/Getty Images)

Colombia’s communist guerrillas, opening peace talks with the government to end a half-century of conflict, on Thursday launched into a fiery critique of the country’s trade-friendly economy and called for its transformation.

The long monologue by rebel commander Luciano Marin, made before reporters in Norway after two days of meetings between the two sides, highlighted the obstacles that lie ahead for negotiations designed to end this Andean nation’s long war.

“We are not discussing foreign investment, nor the model of economic development,” Humberto de la Calle, the government’s lead negotiator, said moments later in response. “None of that will be a subject of discussion.”

The meeting between representatives of the rebel group, the Revolutionary Armed Forces of ­Colombia, or FARC, and President Juan Manuel Santos’s government mark the start of the first official negotiations since 2002. A more substantive round of talks is set to take place in Havana on Nov. 15.

In a series of intensive discussions earlier this year in Cuba, the Colombian government and the rebels came up with a five-point framework agreement for negotiations that establishes a series of goals that are more realistic than those set out in the failed discussions of the past 25 years.

Under that agreement, the FARC’s fighters would reintegrate into society, agrarian reform programs would be put in place, and the rights of victims of the conflict would be addressed.

Of particular interest to the United States is that the FARC and the government would work together to battle the drug trade, from which the rebels draw much of the funding for their war.

In three previous rounds of negotiations going back to the 1980s, discussions were often open-ended, with the FARC pushing for wholesale changes to Colombia’s capitalist economy. In the last series of talks, which began in 1999 and lasted three years, the two sides became bogged down in angry exchanges as the rebels were accused of using a demilitarized zone ceded to them for the talks to hide hostages and armaments and to plan military strikes.

That tough lesson led Santos’s government to pursue talks outside Colombia and under a much tighter time frame, with the president expressing hope that peace would come “in months, not years.”

But Thursday, Marin, who is better known by the alias Ivan Marquez, made it sound as if the FARC was preparing for discussions on topics not included in the framework agreement.

“This can’t be a process against the clock, an express peace, as some are promoting,” said Marin, warning that a rushed process would “only lead to the precipice of frustration.”

He lashed out at Colombian billionaires by name, accusing them of sapping the country’s wealth, and attacked the “transnational vampire” companies that mine in the country. He also called for an end to the concessions that big international mining outfits such as BHP Billiton and Anglo American enjoy.

“Let’s put an end to the monstrosity of those contracts,” said Marin, who also criticized a free-trade pact with the United States.

De la Calle, a former vice president who had negotiated with guerrillas in the past, acknowledged “unjust social differences” in Colombia and said the FARC had “the right to express its ideas.”

But he stressed that the talks in Cuba will focus on the five-point agenda set up in the framework agreement and nothing else. De la Calle also said that the government was committed to talks that moved forward, not discussions that get bogged down.

“If the conversations, I repeat, do not advance, the government will not at any moment allow itself to become a hostage of this process,” he said.

De la Calle said that if the rebels want Colombia to adopt a new economic system, then the FARC’s leaders need to make peace, enter politics and win elections.

Seated across a table from reporters, the commanders of the usually hermetic guerrilla group sounded defiant as they stressed the justice of their cause. But the challenge they face after 48 years of fighting is considerable.

The group numbers 8,000 to 9,000 fighters, half as large as it was a decade ago. And many of the top commanders known to government negotiators in the past are dead, killed in military strikes.

The government also has a powerful benefactor in the United States, which has provided an average of $700 million in mostly military and anti-drug aid each year since 2000.