Mexico City, July 24 (IANS/EFE): The more than 200 stingrays and manta rays found on popular tourist beaches in the eastern Mexican state of Veracruz last week were dumped in the area and did not die from ingesting toxic substances, environmental officials said.

"It is presumed that these animals were discarded and dumped directly in the beach area" because rays "sink to the bottom when they die", federal environmental protection agency chief Francisco Moreno Merino said in a letter to MVS radio.

Examinations of several of the animals turned up lacerations on their bodies around the fins, Merino said.

A total of 219 rays were found July 16 scattered on the popular tourist beach in Chachalacas, a district in the city of Ursulo Galvan, located 35 km from the Gulf city of Veracruz.

Fishermen and tourists notified officials that hundreds of rays had washed up on the beaches in Chachalacas, an area known for its dunes and popular with practitioners of extreme sports.

Investigators have ruled out the possibility that state-owned oil giant Petroleos Mexicanos, or Pemex, is responsible for the incident because no vessels belonging to the company sailed through the area, Moreno said.

"The necropsies showed that the digestive tracts were full of food and no remnants of pollutants or toxic substances were found," Moreno said, adding that authorities planned to step up patrols in the area.