MEXICO CITY - Mexico's foreign minister on Tuesday called the separation of children from immigrant parents at the US-Mexico border "cruel and inhumane" while the leftist front-runner ahead of next month's presidential vote called it "racist."Images published this week of children and youths sitting in concrete-floored cages in US shelter facilities have generated outrage. US officials have defended the measures as a way to secure the border and deter illegal entry."This is a clear violation of human rights and puts children, including those with disabilities, in a vulnerable situation," Foreign Minister Luis Videgaray told a news conference in Mexico City, where he urged the United States to reconsider the practice.Videgaray said the Mexican government had made its position clear to US President Donald Trump's administration and raised the issue with senior United Nations officials, including U.N. Secretary-General Antonio Guterres.Andres Manuel Lopez Obrador, who leads polls ahead of the country's July 1 election, asked Mexican President Enrique Pena Nieto to "act urgently" to stop "that arrogant, racist, inhuman attitude of deporting children, putting them in cages and separating them from their parents.""Soon, very soon, when our movement triumphs, we will defend the migrants from Mexico, Central America, all the American continent, and all the migrants of the world," he said at a rally in Culiacan, the capital of the north-western state of Sinaloa.Of some 1,995 cases registered by US authorities, only around one percent of the children affected were Mexican, and most had already been repatriated, Videgaray said.Among the 21 identified cases of Mexicans separated from their parents was a 10 year-old girl with Down Syndrome who was being held in McAllen, Texas, Videgaray said, adding that the girl's mother was sent to another place.US Attorney General Jeff Sessions announced a "zero tolerance" policy in April that all immigrants apprehended while crossing the US-Mexico border illegally should be criminally prosecuted under the country's criminal entry statute.The policy has led to family separations because when border agents refer apprehended migrants to court for prosecution, parents are held in federal jail to await trial by a judge while the children either remain in border patrol custody or are moved to facilities.Most of the children are from Central America, especially Guatemala, Honduras and El Salvador.Honduras on Monday called for the United States to end the separations, and El Salvador said the policy puts children's health at risk and could cause psychological scars.Videgaray said Mexico would be working closely with the Central American governments.Tensions have run high between Mexico and the United States over the shared frontier ever since Trump ran for office vowing to build a border wall to keep out illegal immigrants.