ROME — At a time of mounting concern about drug-related violence in Mexico spilling over the US border, Pope Francis issued a personal appeal Wednesday on behalf of 43 Mexican students believed to have been massacred and burned in a dump by drug cartels.

“I want to somehow express my closeness to the Mexican people, those present here and those back in the country, on this painful moments of the legal disappearance, but as we know, murder of the students,” the pontiff.

The remarks came in an impromptu addition to Francis’ greeting to Spanish-speaking pilgrims during his regular weekly General Audience in St. Peter’s Square.

Francis said the students, missing since Sept. 26, make visible the “dramatic reality behind drug dealing and trafficking.”

According to reports in the Mexican media, the kidnappings in the southwestern town of Iguala, 120 miles from Mexico City, were allegedly carried out by corrupt police officers who turned the students over to the Guerreros Unidos drug cartel.

Mexico has been the site of intense drug-related warfare for years. It has led to several protests in major cities, with residents accusing the government of President Enrique Peña Nieto of not doing enough to tackle the criminal violence.

In a statement released in late October, the Catholic Archdiocese of Mexico City called for a reconstruction of the country.

“It is urgent that there be a commitment from all sectors of society to combat the immorality, impunity, corruption, and cynicism that has our nation on its knees and covered in shame,” the Mexican bishops said.

“The political class has showed itself to be unworthy and their parties have shown themselves to be totally incompetent for such a large task,” they said.

On Nov. 7, local authorities announced at a press conference that three hitmen had taken responsibility for the crimes against the 43 students.

In taped testimonies, three men identified as the killers said they had taken the students to the dump and used gasoline and tires to burn the remains on the same night they went missing. The mayor of Iguala and his wife, as well as several political allies, police officers, and cartel members, all have been arrested in connection with the case.

During a plane flight to Rome from his visit to South Korea in August, Pope Francis expressed a desire to visit the US-Mexico border next year, a corridor for illegal immigrants and drug trafficking into the United States.

The papal visit would be a part of his highly anticipated trip to the United States to take part in the World Meeting of Families, to be held next September in Philadelphia.

It’s the second time the pope has expressed his support to the families of the students that went missing in Iguala. The first was after the one-month anniversary of the abduction.

On that occasion, Francis said a prayer for the people of Mexico “which is suffering the disappearance of its students and so many other related problems.”