SAN JOSE (Reuters) - Costa Rican prosecutors said on Wednesday they were investigating allegations made in a Mexican newspaper that the government and drug traffickers had held talks last year in an effort to curb a spike in murders.

Prosecutors will probe a potential "breach of duties," the attorney general's office said in a statement hours after El Universal published the expose, which President Rodrigo Chaves rejected as "absurd."

The statement said prosecutors were investigating an international media report but did not name any targets of the investigation.

This year is the deadliest ever for Costa Rica, known for decades as one of Central America's most peaceful countries, with homicides already exceeding the record high for all of last year.

Citing anonymous sources, El Universal reported that Costa Rican security officials contacted local "mafia networks" linked to Mexico's notorious Sinaloa and Jalisco New Generation cartels to ask them to cut the violence.

President Rodrigo Chaves, during a speech, called the story "an absurd hoax" aimed at damaging the image of the country and his government.

The president's office announced that Security Minister Mario Zamora has filed a criminal complaint "given the serious information revealed in the journalistic report" but did not name any targets in the complaint.

"We find it highly suspicious that a news item that seeks to weaken the fight against drug trafficking is published in Mexico and not in Costa Rica," said Zamora, who told Reuters that Costa Rica was experiencing "a Mexicanization of crime" due to the influence of that country's criminal groups.

(Reporting by Alvaro Murillo; Writing by Isabel Woodford; Editing by William Mallard)