Mexican drug traffickers fighting a brutal turf war are attacking priests and preachers who denounce cartel violence, shattering clerics' untouchable aura and breaking honor codes in the world's second-biggest Catholic country.

Gunmen killed a Catholic priest and two seminary students as they left a church in southern Mexico in early June.

Around 1,000 Catholic priests face constant threats from drug gangs across Mexico and as many as 400 have been directly warned to silence their criticisms of narco violence and extortions or be killed, the Mexican Bishop's Conference says.

Although the murdered seminary students are suspected of family ties to drug gangs, most priests say they are targeted for urging parishioners to stand up to traffickers.

"They threatened to burn me and my family alive," said evangelist pastor Bartolome Garcia, who fled a lawless hamlet where he worked near Tijuana on the U.S. border last year.

"They don't like it that we preach and criticize them," said Garcia, who preaches to farmers and the elderly in the bleak, semi-abandoned village of Jacume yards from the U.S. border fence.

Some 12,300 people have died across Mexico in a three-way war between rival cartels and the military since President Felipe Calderon sent thousands of troops to try to crush the cartels on taking office in December 2006.

The carnage of tortured bodies, beheadings and abductions stretches from Mexico's Caribbean to its desert border with the United States and has become a major concern for investors and Washington, worried that violence is overwhelming the country.

Since Mexico's most-wanted man Joaquin "Shorty" Guzman escaped from prison in 2001 and declared war on rival drug kingpins, the fight for supremacy has become so horrific it has broken many rules of the cartel underworld as gangsters even kill children.

Mexicans are increasingly fearful of the heavily armed cartels and the Catholic Church and evangelists are some of the few still speaking out, especially in rural areas dominated by drug gangs where the Mexican government has little control.

The archbishop of the northwestern state of Durango caused a media storm in April when he said that "everyone, except the authorities," knew Guzman was living in the state.

"The church's work in the countryside puts it in direct conflict with the cartels who don't want anyone, least of all priests, witnessing what they are doing," said Victor Sanchez, a security expert at the Tijuana-based research institute Colegio de la Frontera Norte.

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Churches appear willing to face those dangers to win back members as they lose ground to secularism in Mexico.

"We cannot deny the sacraments to anyone, regardless of whether they are involved in illicit activities," Tijuana's Archbishop Rafael Romo told Reuters.

But human rights groups say Catholic priests put themselves at risk of corruption in remote areas where cartels are in control, forced at gun point to baptize kingpins' children or conduct marriages for narco families.

Some are accused of taking money from drug traffickers to pay for church repairs, build chapels and aid local projects.

In Guzman's home state of Sinaloa on the Pacific coast, the cradle of Mexican drug trafficking, rights groups say priests are too complacent and don't check who is behind donations.

The church denies the accusations.

"In a lot of rural areas, the capos provide basic services, they do build or repair chapels because locals ask them to. But this is not sanctioned by the Catholic church and no priest is taking money from them," said Manuel Corral of the Mexican Bishop's Conference.