Two leading civil rights groups sued the federal government Wednesday in hopes of curbing the wide-ranging ability of federal agents to search and seize the smartphones and computers of travelers - including U.S. citizens - as they arrive on American soil but have not yet formally entered the country.

The practice, which remains rare but has grown more frequent in recent years, allows agents in border zones such as the arrivals areas of international airports to sidestep the Supreme Court's landmark Riley decision in 2014 requiring that law enforcement officers get search warrants before examining the contents of digital devices.

That ruling grew from the long-running contention by civil rights groups that modern digital devices carry such massive amounts of data - and such sensitive records including photographs, location data, e-mail communications, videos and Web browsing histories - that they should be afforded full Fourth Amendment protections against searches and seizures without warrants.

Wednesday's suit, filed against the Department of Homeland Security by the American Civil Liberties Union and the Electronic Frontier Foundation, demands stricter legal standard for device searches in border areas. They argue that relatively lax rules established for searching luggage or goods bought in duty free shops should not apply to modern smartphones, tablets and laptop computers routinely carried through borders.

The suit says that the number of such searches - conducted by Customs and Border Protection agents, sometimes with the assistance of Immigration and Customs Enforcement - have grown sharply in recent years and is on track to reach roughly 30,000 in the current fiscal year. That remains a tiny fraction of the several hundred million travelers who enter the nation every year.

"The government cannot use the border as a dragnet to search through our private data," said ACLU attorney Esha Bhandari in a statement. "Our electronic devices contain massive amounts of information that can paint a detailed picture of our personal lives, including emails, texts, contact lists, photos, work documents, and medical or financial records. The Fourth Amendment requires that the government get a warrant before it can search the contents of smartphones and laptops at the border."

A Department of Homeland Security spokesman, David Lapan, declined to comment on the lawsuit, citing department policy against discussing pending litigation. But he said that all travelers are subject to searches, including of their electronic devices, as they enter the United States.

"Over the past few years, CBP has adapted and adjusted our actions to align with current threat information, which is based on intelligence," Lapan said in a statement to The Washington Post. "As the threat landscape changes, so does CBP. Additional CBP officers have been trained on electronic media searches as more travelers than ever before are arriving at U.S. ports of entry with multiple electronics. Despite an increase in electronic media searches during the last fiscal year, it remains that CBP examines the electronic devices of less than one-hundredth of one percent of travelers arriving to the United States."

The lawsuit has 11 plaintiffs - 10 are U.S. citizens and the other is a permanent U.S. resident - including a U.S. military veteran, a NASA engineer and journalists. Several are members of ethnic or religious minority groups.

One of them, Suhaib Allababidi, 40, is a naturalized U.S. citizen born in Kuwait who owns a security business in suburban Dallas. On his return to Dallas/Fort Worth International Airport from a business trip in January, a border control kiosk printed a piece of paper with a black "X" across it rather than an entry document when he tried to cross the border, he said. A CBP agent then brought him to an interview room and asked to examine the two phones Allababidi was carrying.

He agreed to the first search, of an iPhone that he mainly used for business travel to such countries as Kuwait, China, South Korea and Mexico - he was traveling that day from Dubai - but he objected to a search of his personal phone, a Samsung Android device. It included details of his personal life, including photos of his five children and his wife, also a Muslim, without the hijab head covering she ordinarily wears when appearing in public.

The agent, Allababidi said, took custody of the Samsung phone and promised to return it within 30 days. Federal agencies have forensic tools for examining the contents of many smartphones and other devices, though Allababidi's was secured with a numeric pass code consisting of more than 10 digits, likely making it harder to break into the device. Nearly eights months later, the federal agents have not returned the smartphone, he said, forcing him to spend more than $1,000 buying a series of second-hand replacement devices.

"I believe in the constitution of the land," Allababidi said. "No government should go through our private stuff unless they have a warrant."

The suit seeks to establish a stricter standard for such searches and seizures. The ACLU and EFF argue that agents must make a finding of probable cause before seizing a device and get a search warrant - which requires that a judge certify the finding of probable cause - before examining the devices. The civil liberties groups also call for a stricter timetable for returning devices to their owners.

"People now store their whole lives, including extremely sensitive personal and business matters, on their phones, tablets, and laptops, and it's reasonable for them to carry these with them when they travel. It's high time that the courts require the government to stop treating the border as a place where they can end-run the Constitution," said EFF staff attorney Sophia Cope in a statement.

The suit was filed in a federal court in Boston.