Mayor Bill de Blasio on Wednesday ripped as “absolutely ridiculous” allegations by federal border officials that he crossed the US-Mexican border illegally during a visit to an immigration detention area last month in Texas.

The mayor admitted crossing the border to get a better view of a tent city that housed immigrant children separated from their parents, but said it was done with all the proper approvals.

“The border agents … let our cars cross the American border into Mexico at a normal checkpoint,” he said after an unrelated press conference on public housing in Brooklyn.

“We came back the exact same way, both times showed passports, went through with the approval of the agents at the entry point,” he added. “At no point did we disregard any instructions from federal authorities, period.”

He said his party crossed the border to get a better view of the tent city, which he and other mayors from across the country had been prohibited from entering.

De Blasio’s rebuttal was aimed at a letter from a US Customs and Border Patrol official to the NYPD that alleged the mayor and his security detail violated border crossing laws.

It cited claims by an agent that the group ignored his orders to stay put after he had told them of the violation, according to the Associated Press.

De Blasio charged the letter was an attempt by the Trump administration to deflect criticism of the separation policy, which has since been altered.

Thousands of kids separated from their parents — including hundreds transported to New York City — have yet to be reunited.