LOS ANGELES, United States (AFP) — Rights activists in the United States called Wednesday for the country’s iconic Greyhound buses to stop allowing immigration police without warrants to interrogate and arrest passengers.

The agents, with the acquiescence of Greyhound, have been staging increasingly frequent raids to question foreign-looking passengers about their citizenship and demand papers, says the American Civil Liberties Union (ACLU).

“Greyhound is in the business of transporting its passengers safely from place to place,” said Jennie Pasquarella, director of immigrants’ rights for the ACLU Foundations of California.

“It should not be in the business of subjecting its passengers to intimidating interrogations, suspicion-less searches, warrantless arrests and the threat of deportation.”

The ACLU listed several undated examples of what it called unlawful interrogations, including an incident in Indio, southern California, where agents detained a Los Angeles man whose “shoes looked suspicious.”

It listed further incidents in Vermont, Washington and Michigan.

US Customs and Border Patrol told AFP enforcement action away from the border was a decades-old tactic that prevented trafficking, smuggling and other criminal activity on public transport.

“These operations serve as a vital component of the US Border Patrol’s national security efforts,” a spokesman said in a statement, adding that the law didn’t require warrants.  

“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,” he added.

“They have the authority to question individuals, make arrests, and take and consider evidence.”

Greyhound said in a statement it was required to comply with the law but would do “everything legally possible” to minimise disruption to passengers.

“Greyhound has opened a dialogue with the Border Patrol to see if there is anything that can be done to balance the enforcement of federal law with the dignity and privacy of our valued customers,” it added.

The ACLU, however, maintains that court decisions stemming from the Fourth Amendment permit the company to block the interrogations without warrants or probable cause.