A Texas National Guard who was deployed to prevent migrants entering the US has been arrested on suspicion of smuggling a migrant across the border in a government car.

Specialist Savion Amari Donovan Johnson sparked a high speed chase with police in Brackettville, Texas, after he abruptly turned around at border checkpoint as a migrant jumped out.

The 26-year-old's sudden change of direction just ahead of a checkpoint on Highway 674 led to a 15-mile chase at speeds of more than 100mph.

Sheriff Brad Coe said Johnson was a member of the Texas National Guard assigned to Operation Lone Star - a project to stop migrants breaching the Eagle Pass crossing.

Johnson was arrested after being pulled out of his silver SUV given to him for work.

The vehicle was finally stopped by road spikes.

"Why you running, dude?" the arresting KCSO deputy asked Johnson.

He replied: "I got very, very scared," as other police were heard saying a Hispanic man was spotted moving to the south.

LATEST DEVELOPMENTS:

US immigration sparks outrage after adding new gender option to formsMigrants who broke through razor wire on Texas border slapped with rioting chargesMigrant stabbed to death at camp near Dunkirk as violence grips northern France

"I'm so f**king stupid," Johnson said, to which the deputy agreed: "Yeah, you are f**king stupid, man."

"Do you know how many people you could have f**king killed, man? Jesus Christ."

Police said Johnson was reportedly offered $5,000 to $6,000 to take the man over the border undetected.

Texas Governor Greg Abbott's Office condemned Johnson following the incident.

Press secretary Andrew Mahaleris said: "If the allegations are true, the accused is a traitor and criminal.

"We have zero tolerance for Texans who violate laws that directly contradict the mission we are seeking to achieve.

"The accused's illegal smuggling may subject him to a mandatory minimum prison sentence of at least 10 years. He deserves more."

Johnson was charged with human smuggling, felony evading arrest and unlawful weapons possession.