A journalist was found decapitated Wednesday in a violence-plagued area of eastern Mexico, police said, the latest in a string of killings in one of the world's most dangerous countries for reporters.

Julio Valdivia of the newspaper El Mundo de Veracruz is the fifth journalist slain in Mexico this year, according to media watchdog Reporters Without Borders (RSF).

Hugo Gutierrez, security minister and head of the police in eastern Veracruz state, condemned the "cowardly murder" of the 41-year-old reporter.

"In coordination with the state attorney general's office we will exhaust all resources to find those responsible," he said in a statement.

Valdivia's body was found with his motorcycle on a train track in a mountainous area of the municipality of Tezonapa, according to his newspaper.

It said he had covered a confrontation between police and suspected criminals the previous day.

Valdivia "worked in a complicated area where there are criminal groups," said Ana Laura Perez of the State Commission for the Attention and Protection of Journalists, a government body.

"It must be investigated if he had reported something that bothered these criminal groups."

Veracruz is a flashpoint in turf wars between Mexico's rival drug cartels as well as the country's deadliest state for media workers.

In March, journalist Maria Elena Ferral was shot dead by two assailants on motorbikes when getting into her car in Veracruz.

RSF regularly ranks Mexico alongside war-torn Syria and Afghanistan as the world's most dangerous countries for news media. 

The watchdog urged the authorities to probe whether Valdivia was murdered because of his work.

"All lines of inquiry must be exhausted, mainly those that have to do with his journalism because he worked in an area marked by violence," Balbina Flores, the group's representative in Mexico, told AFP.

More than 100 reporters have been murdered since 2000 in Mexico, where asking questions about political corruption or powerful drug cartels can be a deadly business.

Only a fraction of those crimes have resulted in convictions.

In one rare such sentencing, a man convicted of ordering the 2017 murder of prominent journalist Miroslava Breach was condemned last month to 50 years in prison.