Peace talks between the FARC and Colombia's government resumed Monday after a three-week break amid rebel criticism of recent remarks by the Latin American country's leader.

President Juan Manuel Santos claimed in a November 26 speech that the FARC "had realized they were on a road to nowhere" and that pressure from the Colombian army had forced them to the negotiating table.

"These statements do not help in the pursuit of confidence between the two parties that are trying to carry out a peace process," Ivan Marquez, the FARC's delegation chief, told reporters.

Marquez is the second in command at the Revolutionary Armed Forces of Colombia, which has been in talks with the government since November 2012 in an attempt to end their near 50-year conflict.

Considered Latin America's longest-running insurgency, it has left hundreds of thousands dead and displaced more than 4.5 million.

In his speech to members of the military, Santos had praised Plan Colombia, a $9 billion US funded anti-narcotics effort launched in 2000 that included a counter-insurgency element.

"Santos himself revealed that this was not a plan against drug trafficking but a counter-insurgency plan conceived to quell social unrest," Marquez said.

He went on to say that recent revelations by the Washington Post about a secret CIA program that helped government forces eliminate rebel leaders -- including the 2008 killing of the FARC's then-second in command Raul Reyes in Ecuador -- proved "total American interventionism."

The 2008 incident triggered a diplomatic crisis between Bogota and Quito, with Ecuador suspecting the attack was orchestrated with the help of the United States, despite denial from Colombian authorities.

As usual, the government delegation led by former vice president Humberto de la Calle made no comment at the start of the latest negotiations, held in the Cuban capital Havana. The last round, focused on the coca trade, wrapped up on December 20.

But Santos said Monday he was more optimistic about the peace talks today than a year ago.

"We know we still have a long way to go," Santos told RCN radio, saying the process was not an easy one.

"It is full of contradictions and complexities but we must stay the course."

He also expressed hope that a deal could be reached "as soon as possible," adding that the Colombian people would have the final say about whether to endorse it.

Founded in 1964, the FARC is considered Colombia's largest rebel group and has 7,000 to 8,000 fighters.

The current peace talks are a fourth attempt to end the bloody strife.