Colombia's government has deployed 700 additional security force members to this violence-wracked Pacific port city, which has been plagued by killings, dismemberments and forced disappearances.

Defense Minister Juan Carlos Pinzon accompanied the troop deployment Friday in Buenaventura, where the discovery of so-called "casas de pique" (chop-up houses) - sites in which victims are allegedly dismembered alive - has riled public opinion.

The militarization of some parts of the city, ordered weeks ago by President Juan Manuel Santos, came a day after New York-based Human Rights Watch issued a report indicating that "entire neighborhoods were dominated by powerful paramilitary successor groups."

Those gangs, known as Los Urabeños and La Empresa, both successors to the now-defunct AUC paramilitary federation, are fighting a bloody battle for control of arms and drug trafficking in that strategic and largely Afro-Colombian port city.

The defense minister visited neighborhoods in the city's Bajamar sector, whose stilt houses protect residents against tidal flooding but not from the scourge of drug-related violence.

"You can't go that way!" some children shouted when Pinzon walked down one street under heavy armed guard, referring to one of the so-called "invisible borders" drawn by the gangs in Buenaventura's urban center.

Crossing those unmarked frontiers can often be a death sentence for local residents.

Thus far this year, more than 500 people have been killed by gangs in Buenaventura and some of them have been dismembered.

Buenaventura also has the highest rate of forced disappearances in Colombia, with 153 cases between 2010 and 2013, according to official figures.

More than 13,000 people fled their homes between January and October of last year, although HRW says the real figure is much higher and that "nowhere in Colombia is the problem of forced displacement worse today than in Buenaventura."

Some residents told Pinzon that the lack of job opportunities was the root cause of violence in the city, where 50 percent of the population is unemployed and 80 percent of people live below the poverty line.

A source with the city's police command told Efe the majority of the population opposes the military deployment and that it would not succeed in eradicating the violence.

"What Buenaventura needs is social investment, for young people to work because there's nothing to do here," the source added.

The deployment Friday of 700 police, army soldiers and marines to Buenaventura brings the number of security force members in that city of a half million people to 2,400, Pinzon said. EFE