The Associated Press
WASHINGTON - New York City Mayor Bill de Blasio and his security detail violated both Mexican and U.S. immigration laws by crossing the border on foot during a visit near El Paso, Texas, U.S. Customs and Border Protection alleges in a letter obtained by The Associated Press.

The mayor on Wednesday called the allegation “absolutely ridiculous.”

De Blasio, a fierce critic of the Trump administration’s immigration policies, went to the Texas border with about 20 other mayors from around the country on June 21, the day after President Donald Trump signed an order stopping family separations at the border.

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More than 2,300 families were separated as a result of the administration’s zero tolerance policy, which criminally prosecutes anyone caught crossing illegally. The mayors said Trump had failed to address a humanitarian crisis of his own making.

De Blasio went to a holding facility for immigrant children but was denied entry. He then went to Mexico to get a better view of the facility. The New York Police Department runs de Blasio’s security detail.

According to the letter, a uniformed Border Patrol agent noticed a group standing in the Rio Grande flood plain south of the Tornillo, Texas, port of entry, taking photos of the holding facility. The agent asked if anyone from Border Patrol or public affairs was there to authorize their presence. An NYPD inspector said no, according to the letter, and when the agent asked the group how they arrived, they pointed to Mexico.

The agent told them they’d crossed the border illegally and asked them to remain there while he got a supervisor and took them to an official crossing for an inspection per federal law, according to the letter. But the group disregarded the order, walking back to their vehicles and driving back to Mexico, according to the letter. They re-entered by car through a port of entry about three hours later, the letter said.

De Blasio said border agents approved the crossing after his security detail asked to venture into Mexico so the mayor and other elected officials could get a different view of facility holding youths.