The United Nations said Monday it was concerned by a Peruvian proposal to sanction oil operations despite a legacy of heavy pollution and rights abuses.

Human rights experts working for the United Nations said there were frustrated with a Peruvian government decision to start operations in the northern Loreto region in one of the more desolate parts of the Amazon Rainforest. The operation comes despite an agreement between aboriginal groups and the state-owned Petroperu to clean areas contaminated by more than 40 years of oil spills.

"Companies extracting oil in this region have left behind a toxic mess with disregard for the rights of affected communities and laws of Peru," U.N. special envoy for human rights and hazardous substances Baskut Tuncak said in a statement.

The Peruvian government in recent years declared environmental emergencies over parts of Loreto because of a legacy of oil spills.

U.N. experts say water tests from the Loreto region have revealed high levels of heavy metal contamination, with nearly all of the children in the area testing positive for toxic metals in their bloodstream.

"Peru has obligations to clean up the toxic oil spilled to protect the rights of people in the region, and to hold the companies accountable for their failure to respect human rights, before re-licensing the land and making an awful situation worse," Tuncak said.

The warning comes after world delegates emerged from a climate summit in Lima, Peru, with a clear vision of the path forward to address climate change. Government delegates arrived with a sense of urgency and left with a "fresh wave of positivity," U.N. climate chief Christiana Figueres said in a statement.