Mexican President Andres Manuel Lopez Obrador has rejected calls for the United States military to intervene to stem drug cartel violence in Mexico, saying such a move would violate the country’s sovereignty.

During a news conference on Thursday, Lopez Obrador said his government was “not going to permit any foreign government to intervene in our territory, much less that a government’s armed forces intervene”.

“In addition to being irresponsible, it is an offence to the people of Mexico,” he said, adding that Mexico “does not take orders from anyone”.

On Wednesday, Texas Republican Dan Crenshaw released a message in Spanish asking Lopez Obrador why he opposed a proposal the congressman introduced in January, authorising US military force to target drug cartels in Mexico.

“The cartels are war with us — poisoning more than 80,000 Americans with fentanyl every year, creating a crisis at our border, and turning Mexico into a failed narco-state,” Crenshaw said in a statement on January 12 about the proposed legislation.

“It’s time we directly target them. My legislation will put us at war with the cartels by authorizing the use of military force against the cartels. We cannot allow heavily armed and deadly cartels to destabilize Mexico and import people and drugs into the United States.”

Republican Senator Lindsey Graham on Monday also said in a Fox News interview that it was time to “put Mexico on notice”. He advocated introducing legislation to classify some Mexican drug cartels as “foreign terrorist groups”.

Drug cartel violence in Mexico has come under renewed scrutiny in the US after four Americans were kidnapped by armed men last Friday.

The four Americans were hauled off in a pick-up truck after “unidentified gunmen fired upon” their vehicle, the Federal Bureau of Investigation (FBI) said in a statement at the weekend.

“All four Americans were placed in a vehicle and taken from the scene by armed men.”

A Mexican citizen was killed in the incident, which took place as drug cartel factions tore through the streets, Tamaulipas Governor Americo Villarreal said.

The US citizens had crossed into the northeastern Mexican city of Matamoros, across the border from Brownsville, Texas, for a medical procedure. The city, however, has been beset by violence linked to drug trafficking and other organised crime.

Mexican authorities frantically searched as the cartel moved the four Americans around, even taking them to a medical clinic, “to create confusion and avoid efforts to rescue them”, the region’s governor said.

Bodies and survivors were ultimately found on Tuesday in a wooden shack in a rural area east of Matamoros, guarded by a man who was arrested, according to the state’s chief prosecutor, Irving Barrios.

Two of the abducted individuals had been killed while the other two were discovered alive, one with a gunshot wound to the leg.

The survivors were whisked back to US soil on Tuesday in a convoy of ambulances and SUVs, escorted by Mexican military Humvees and National Guard trucks with mounted machine guns.

On Thursday, someone claiming to be from the Mexican drug cartel that was allegedly involved in the kidnapping condemned the violence and said the group had turned the perpetrators over to authorities.

In a letter obtained by The Associated Press news agency through a Tamaulipas state law enforcement source, the Scorpions faction of the Gulf cartel apologised to the residents of Matamoros, the Mexican woman who died in the shooting, and the four Americans and their families.

Drug cartels have been known to issue communiques to intimidate rivals and authorities but also, at times, to smooth over situations that could affect their business.

“We have decided to turn over those who were directly involved and responsible in the events, who at all times acted under their own decision-making and lack of discipline,” the letter reads.

It added that the individuals involved had gone against the cartel’s rules, which include “respecting the life and wellbeing of the innocent”.

Still, the fatal kidnappings and backlash could complicate delicate efforts to foster closer collaboration between the US and Mexico on immigration and the trafficking of drugs, among other issues.

Lopez Obrador said on Thursday that he would begin a public information campaign aimed at Mexicans in the United States about the Republican-led proposal for US military intervention.

If Republican lawmakers try to “use Mexico for their propagandist, electoral and political purposes, we will make a call to not vote for that party”, the Mexican president said. (Al Jazeera)

•Mexico 'does not take orders from anyone', President Andres Manuel Lopez Obrador says [Henry Romero/Reuters]

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