A United Nations office in Guatemala on Tuesday decried that a major river, Rio La Pasión, in the Central American country has been heavily contaminated with pesticides.

The pollution in the Río La Pasión is apparently caused by plantations producing African palm oil and affects thousands of residents, the international organization detailed, according to AFP.

"These people live off the river, they use water for consumption and personal hygiene, and they also feed on fish," U.N. resident coordinator Valerie Julliand said about local residents at a news conference. "What we want is to make sure that no one forgets about this case, regardless of time, and to make sure there's justice, to avoid repetition."

The large-scale contamination in the 220-mile-long river had first been noted because of a massive fish die-off in the Petén Department, located near Guatemala's northern border with Mexico. Some 23 fish species have been affected, and the country's National Council of Protected Areas suspects that damage may also have been done to 21 varieties of mammals, birds and reptiles, the newspaper deatiled.

The U.N. has declared the Río La Pasión an "ecological disaster" that beyond the environmental threat also has had a "psychological impact" on local families, compounding the situation of poverty with the experience of "mourning the loss of the river," Julliand told teleSUR.

The official called for an investigation into those responsible for the contamination. Guatemalan prosecutors for crimes against the environment, though, said in June that their probes so far had not yielded enough evidence to justify any arrest warrants, Siglo 21 recalled.

Julliand noted that according to U.N. estimates, each palm oil plantation generates between 2.5 and 3.75 metric tons of industrial waste for each ton of product produced. The director of the U.N. Human Rights Office in Guatemala, meanwhile, added that the plantations have increased in size by approximately 270 percent between 2003 and 2013; they now operate on a surface of about 130,000 hectares, Alberto Brunori said, according to Telemetro.