A pair of illegal Mexican immigrants nabbed at the US border in Texas broke free after trying to strangle a female border agent — only to be nabbed nearby by quick-thinking immigration authorities.

The drama unfolded Monday, when the two migrants — Juan Carmen Padron Mendez, 29, and Juan Carlos Padron Barron, 23 — were picked up trying to enter the country illegally and taken into custody, the US Attorney’s Office in the Southern District of Texas said.

The migrants were placed in plastic flexicuffs and put in the back of the unnamed border agent’s squad car to be transferred to a holding facility in Houston — when things went south.

The officer was stopped at a red light when she heard a seatbelt unbuckling, and soon had Mendez wrapping his hands around her neck and choking her, prosecutors said.

Both migrants then grabbed their belongings and took off on foot while the cop called for backup.

Mendez and Barron were picked up again nearby and, this time, were taken to the detention facility, where they were charged with assault, resisting arrest and impeding a federal officer, and are being held pending a return court appearance on Wednesday.

“The Southern District of Texas has zero tolerance for those who assault law enforcement,” US Attorney Nicholas Ganjei said in a statement this week.

“Let it be known: if you lay a hand on an officer, deputy or federal agent, SDTX will do whatever it can to put you in federal prison for as long as the law will allow,” Ganjei said. “You’ve been warned.”

Prosecutors said Mendez and Barron face up to 20 years in federal prison and fines of up to $250,000 on the assault charges, and another year and $100,000 on the escape.