Mourners packed into a church in Mexico's troubled Gulf coast state of Veracruz yesterday for the funeral of one of the two priests found to have been killed there on Monday.

It was standing room only at the church in the community in Paso Blanco, while others huddled outside and listened through windows.

At the front of the church, a large banner showed a picture of the young Rev Jose Alfredo Suarez de la Cruz, who was ordained only a few years ago and arrived at his post in the city of Poza Rica just a month before he was killed, according to the LA Times.

"You are a priest for always," the banner read.

Suarez and the Rev Alejo Nabor Jimenez were last seen on Sunday in Veracruz 's northern city of Poza Rica. Their bodies were discovered riddled with bullets the following day on a roadside.

State prosecutors have said that they have identified a suspect in the murders. They have also said that they believe the clerics knew their attackers and had been drinking with them before the gathering "turned violent".

However, some parishioners are sceptical of this theory and suspect organised crime, with Poza Rica being plagued by killings and disappearances.

A priest said during yesterday's service: "Unfortunately, Poza Rica is a very severe place in [terms of] security".

Pope Francis sent a letter of condolences, calling the murdered clerics "victims of inexcusable violence". The letter was signed by Cardinal Pietro Parolin, the Vatican secretary of state.

Bishop Jose Trinidad Zapata Ortiz of the city of Papantla, near Poza Rica, said in a statement released by the Mexican Conference of Bishops: "Yet again we confirm that violence and insecurity have taken root in our society. We hope that authorities clear up the crime and that such a regrettable loss of our brothers serves for the arrival of the peace we all desire so much."

The Catholic Media Center says that 28 priests have been killed in Mexico since 2006, not counting this week's murders, and that Veracruz, Guerrero and Mexico State are the most dangerous in the country.

The US State Department wrote in its 2015 International Religious Freedom report that priests in Mexico are "victims of extortion attempts, death threats and intimidation by organized criminal groups".