The Mexican government on Tuesday condemned the killing of an illegal Mexican migrant on the U.S.-Mexican border.

In a diplomatic note presented by Mexico's Embassy in Washington, the Mexican government expressed "firm condemnation" over the shooting death of 22-year-old Francisco Francisco Javier Dominguez Rivera during a confrontation with the U.S. Border Patrol.

The Mexican government also voiced in the note its serious concern over "the recurrence of such incidents", and demanded an exhaustive investigation to punish those held responsible, according to a news release from the Department of Foreign Relations.

Seven Mexicans, including Dominguez Rivera and two brothers, were confronted with the U.S. Border Patrol while crossing the Arizona desert on the border with the United states.

The Border Patrol said that they detained six of them peacefully, but Dominguez Rivera was shot dead during a fight with an agent, who believed his life was endangered.

In the U.S. state of Arizona, an FBI spokesman said on Tuesday that the case was already under investigation, and that there could also be civil rights investigation.

Source: Xinhua