Human rights defenders, clergymen and academics said they will petition the International Court of Justice to investigate the 2010 massacre of 72 mostly Central American migrants in San Fernando, a city in the northeastern Mexican state of Tamaulipas, amid persistent impunity in the case.

More than 30 activists gathered in Mexico City Tuesday to pay tribute to the 72 Honduran, Salvadoran, Guatemalan, Ecuadorian and Brazilian migrants who were killed in that municipality in August 2010 by suspected members of the Los Zetas criminal gang.

The Zetas, a gang of special forces deserters turned outlaws that is regarded as Mexico's most violent drug cartel, apparently killed the migrants after they refused to work as couriers or enforcers.

During the ceremony at the offices of the Mexican Federal District's Human Rights Commission, Mexico City's ombud's office, the participants lamented that no steps have been taken to prosecute any federal, state or municipal authorities - whether civilians, police or military - whose actions or omissions contributed to the tragedy.

They therefore want the case tried at The Hague, Netherlands-based ICJ, the United Nations' highest judicial body.

"My conclusion is that the goal of the Mexican government's immigration policies is for migrants not to make their way to the (United States)," the bishop of the northern Mexican city of Saltillo, Raul Vera Lopez, said.

Others taking part in the event included Catholic priest Pedro Pantoja, who runs a migrant shelter in Saltillo; Agnieszka Raczynska, executive secretary of the National Network of Civil Human Rights Organizations; and Pedro Gonzalez Gomez, a representative of the Indigenous Migrants' Assembly.

Julio de Silveira Moreira, member of the Brazilian Association of People's Lawyers, said Mexican authorities have shown their "inability" to solve the Tamaulipas massacre.

"They also have been unable to send identified bodies of the slain migrants" back to their countries of origin, the attorney said.

In the case of the four Brazilian victims, family members who disobeyed instructions not to open their coffins found only bones inside and refuse to recognize those remains as belonging to their relatives, he added.

Around 70,000 migrants have disappeared while attempting to make the trek to the United States via Mexico since outgoing President Felipe Calderon took office in December 2006, Jose Jacques y Medina, a member of the Mesoamerican Migrant Movement, said.

An estimated 300,000 Central Americans undertake the hazardous journey across Mexico each year on their way to the United States.

The trek is a dangerous one, with criminals and corrupt Mexican officials preying on the migrants.

Gangs kidnap, exploit and murder migrants, who are often targeted in extortion schemes, Mexican officials say.

Central American migrants follow a long route that first takes them into Chiapas state, which is on the border with Guatemala, walking part of the way or riding aboard freight trains, buses and cargo trucks.

The flow of migrants has increased markedly in the northern and northeastern parts of Mexico since U.S. officials increased security along the border in the northwestern part of the country.

A total of 46,716 Central Americans were deported from Mexico between Jan. 1 and Nov. 30, 2011, the National Migration Institute, or INM, said in a report released earlier this year.

The majority of the migrants - 41,215 - were men and nearly half, some 23,560, were from Guatemala, the INM said. EFE