Mexico's Profepa environmental protection agency has filed a criminal complaint against state oil monopoly Petroleos Mexicanos "for the deaths of turtles and contamination of beaches and mangrove swamps" in the wake of an oil spill in the southern state of Oaxaca.

The criminal complaint lodged Wednesday with the federal Attorney General's Office "is based on the results of laboratory analysis conducted on intestine and liver samples taken from turtles found dead during inspection tours" in the region.

On Aug. 11, a loading buoy (an installation used to load crude oil on to tanker ships at sea) sank at a spot off the coast of Oaxaca facing the Salina Cruz refinery, causing crude to spill onto six beaches in that state.

Specialists from the National Polytechnic Institute have assessed the damage in recent weeks and confirmed the damage to turtles, beaches and mangrove vegetation in the area.

"In the case of wildlife, 13 dead animals were found and collected, 12 of them on Morro Ayuta beach in San Pedro Huamelula and the other on Chipehua beach in Santa Gertrudis Miramar," Profepa, a division of the Environment Secretariat, said in a statement.

The turtles "showed systemic impairment and damage and intoxication from hydrocarbons, which very likely caused their deaths," the statement added.

In the mangrove ecosystem, "oil impregnation was found in trunks, stems and leaves" near the Cangrejo and Chipehua beaches, "basically affecting the species known as white mangrove (Laguncularia racemosa) and button mangrove (Laguncularia racemosa).

Both of those mangrove shrubs and olive ridley turtles are protected wildlife species in Mexico, the former "at risk of extinction" and the latter listed as "endangered."

Profepa again called on the state oil firm to comply with measures requiring it to clean up and recover oil spilled in the affected areas.

For its part, the National Human Rights Commission, Mexico's equivalent of an ombud's office, has opened an "ex-officio" inquiry into the oil spill, which it has described as "worrying." EFE