Two US citizens were detained by a federal Border Patrol agent in Montana after he overheard the women speaking Spanish at a gas station convenience store, according to a report.

Ana Suda and her friend Mimi Hernandez had gone to the store in Havre around midnight last Wednesday to pick up milk and eggs when they were stopped by the uniformed agent.

Suda says she and her pal — who are both Mexican-American and are fluent in Spanish — were waiting in line to pay when the agent, who identified himself as “Agent O’Neal,” questioned them.

“We were just talking, and then I was going to pay,” Suda told the Washington Post. “I looked up [and saw the agent], and then after that, he just requested my ID. I looked at him like, ‘Are you serious?’ He’s like, ‘Yeah, very serious.’”

When the encounter moved into the parking lot, Suda pulled out her cellphone and began recording the incident.

When Suda asks the agent why he is detaining them, he responds that it’s because they were speaking in Spanish.

“Ma’am, the reason I asked you for your ID is because I came in here, and I saw that you guys are speaking Spanish, which is very unheard of up here,” the agent is heard saying in the clip.

The agent goes on to say that “it has nothing to do” with racial profiling after Suda mentions the practice.

“It has to do with you guys speaking Spanish in the store, in a state where it’s predominantly English-speaking,” the agent says in the video.

When Suda asks if it is illegal to speak Spanish in Montana, the agent responds: “It’s not illegal. It’s very unheard of over here.”

According to the Washington Post, Suda, 37 — born in El Paso, Texas, and raised in the Mexican city of Ciudad Juárez — has spent most of her adult life in the US with her husband and daughter.

Hernandez was born in central California, Suda said.

Suda said the encounter with the border patrol agent lasted about 40 minutes.

“I was so embarrassed … being outside in the gas station, and everybody’s looking at you like you’re doing something wrong. I don’t think speaking Spanish is something criminal, you know?” Suda told the news outlet. “My friend, she started crying. She didn’t stop crying in the truck. And I told her, we are not doing anything wrong.”

A US Customs and Border Protection rep told the Washington Post in a statement that the agency is reviewing the incident.

“U.S. Customs and Border Protection agents and officers are committed to treating everyone with professionalism, dignity and respect while enforcing the laws of the United States,” the agency said.

“Although most Border Patrol work is conducted in the immediate border area, agents have broad law enforcement authorities and are not limited to a specific geography within the United States. They have the authority to question individuals, make arrests, and take and consider evidence.”

Meanwhile, Suda, according to the paper, is planning to contact the American Civil Liberties Union to seek legal counsel.

“I just don’t want this to happen anymore,” Suda said. “I want people to know they have the right to speak whatever language they want. I think that’s the most important part, to help somebody else.”