The Shottas and Spartanos gangs have battled to divvy up control of the city, itself a crucial conduit for both legal trade as well as for cocaine flowing to the United States.

But on Tuesday presidential peace advisor Danilo Rueda and gang representatives met publicly for the first time.

In addition to the talks, the government has also introduced work initiatives to provide gang members with alternatives to a life of crime. The city of 350,000 has a poverty rate of 40 percent and one in four people are unemployed.

"We believe that they are on the right path to be able to achieve these transformations without violence in Buenaventura," Rueda said.

Delegates from the Catholic Church, the United Nations, the Organization of American States and the governments of Norway, Sweden and Switzerland were also present.

The rivalry between the Shottas and the Spartanos is thought to have cost some 300 lives, with both gangs dealing in drugs and extortion.

But it is unclear if there will be legal amnesty on the table for gang members who participate in the talks. A bill establishing the conditions and incentives has yet to be approved in Congress, where Petro lacks a majority.

Experts and gang members have criticized the fact that the dialogue is taking place without a legal framework backing it up.

But gang representatives on Tuesday said they were ready to engage.

"(We came) for those boys and girls, so that they don't take up arms later on," said Jimmy Garcia, a community leader representing the Shottas.

"The people want peace," said Spartanos spokesman Felix Orlando Luna. "Between all of us, we can build peace and move forward."

The government is also in talks with criminal groups in the city of Medellin and has engaged in negotiations with guerillas from the National Liberation Army (ELN).

It will soon also negotiate with the main offshoot of FARC rebels that did not demobilize in the 2016 peace deal with that group.