World Bulletin / News Desk

The Colombian government is set to sit down for a first round of peace talks with the ELN rebel group Wednesday, seeking to end a 53-year conflict that has killed more than 260,000.

The negotiations with the National Liberation Army (ELN) -- the country's last active rebel group -- mark a new milestone in the Colombian peace process, after President Juan Manuel Santos's government sealed an historic accord with the country's largest rebel group, the Revolutionary Armed Forces of Colombia (FARC), in November.

The small ceremony took place at a Jesuit retreat outside the capital Quito.

"We have before us the opportunity to finally turn the page on this war," said the government's chief negotiator, Juan Camilo Restrepo.

But experts warn the ELN will be a tougher negotiating partner than the FARC.

There was friction between the two sides even as they celebrated the formal opening of talks.

Restrepo warned the rebels that if they fail to give up kidnapping, "it will be very difficult to advance."

The ELN's chief negotiator, Pablo Beltran, for his part called on the government to "take responsibility" for its actions during the conflict -- saying the rebels were prepared to do the same.

Colombia is the scene of the last major armed conflict in the Americas.

South America's third economy and the world's biggest cocaine producer, the country has been torn since the 1960s by fighting that has drawn in multiple leftist rebel groups, right-wing paramilitaries, drug gangs and the army.

November's landmark peace accord with the FARC, the oldest and largest rebel group, leaves the ELN the last active guerrilla insurgency.

It has an estimated 1,500 fighters, mostly in the north and west.