A journalist has been murdered in northwestern Mexico, authorities said Thursday -- the ninth such killing so far in a particularly violent year for the country's press.

The body of Luis Enrique Ramirez, 59, was found on a dirt road in Sinaloa, the state's attorney general Sara Quinonez said on Twitter.

Sinaloa is the stronghold of notorious narco kingpin Joaquin "El Chapo" Guzman's cartel and one of the Mexican states most affected by drug-related violence.

Ramirez was a columnist for the local newspaper El Debate and founder of the news site Fuentes Fidedignas.

He previously worked for the national newspapers El Financiero, El Nacional and La Jornada.

His columns scrutinized the actions of politicians in his region.

In the last article before he died, Ramirez reported that a man, whom he did not identify, had insulted him in a restaurant.

His body was found on the outskirts of the state capital Culiacan, a day after he went missing.

"It was definitely a murder," said Balbina Flores, representative of media rights group Reporters Without Borders (RSF), adding that the corpse was found wrapped in plastic.

Ramirez is the ninth journalist killed so far this year in Mexico, according to RSF.

Media freedom group Article 19 called on authorities to ensure "a prompt, impartial and diligent investigation" into Ramirez's murder.

In 2015, Ramirez said he felt "imminent danger" that he might be killed, referring to the earlier murder of a colleague.

The Latin American nation is on course for one of its deadliest years yet for the press, prompting calls from rights groups for authorities to end a culture of impunity.

More than 150 journalists have been murdered since 2000 in Mexico, one of the world's most dangerous countries for the media, only a fraction of which have resulted in convictions.

The victims are often reporters working for local media in states plagued by drug cartel-related violence.

They include acclaimed journalist and AFP contributor Javier Valdez -- known for writing articles critical of powerful gangs such as the Sinaloa cartel -- who was shot in Culiacan in 2017.

The United States and the European Parliament have urged Mexico to ensure adequate protection for journalists following the recent string of killings.

President Andres Manuel Lopez Obrador has vowed "zero impunity" for the crimes and accused Washington of "interfering."

His spokesman Jesus Ramirez renewed the vow on Thursday and said the government condemned Ramirez's murder.

"We will reinforce security measures for journalists. There will be no impunity," he tweeted.

Last week the government blamed drug traffickers for the January murders of journalists Lourdes Maldonado and Margarito Martinez in the northwestern border city of Tijuana that triggered international condemnation.