The number of people arriving at the U.S.-Mexico border who expressed a fear of returning to their home countries jumped 67 percent during the government’s 2018 fiscal year, according to statistics released Monday by U.S. Customs and Border Protection, data officials characterized as a sign that frivolous asylum claims have surged.

At official U.S. border crossings, known as ports of entry, nearly twice as many migrants seeking to enter the United States without authorization stated a fear of persecution or harm — typically the first step in the asylum process — during the 12-month period that ended in September. Of the 124,511 foreigners deemed “inadmissible” by CBP officers, 31 percent made a fear claim, the figures show, up from 16 percent in fiscal 2017.

Fear claims also rose among those arrested for attempting to enter the United States illegally from Mexico. Of 396,579 migrants taken into custody after making an illegal border crossing during the 2018 fiscal year, 54,690 made a fear claim.

While that was a significant increase in the number of claims processed overall, the percentage of illegal border-crossers who stated a fear of returning to their home countries was nearly unchanged, rising from 13 percent in fiscal 2017 to 14 percent in the past fiscal year.

In recent weeks, Homeland Security agencies have published statistics they say are indicators of a “crisis” at the border, particularly as more Central American parents arrive with children and turn themselves in to U.S. agents. After a cursory interview with an asylum officer to determine if their fears are credible, most asylum seekers are released from custody in a matter of days, the enforcement approach Trump bewails as “catch and release.”

Homeland Security officials said such policies have created legal loopholes that are inviting abuse and triggering a surge in illegal migration. CBP stopped more than 62,000 people attempting to enter the United States without authorization in November, the highest one-month total of Trump’s presidency.

“These numbers reflect a dramatic increase in initial fear claims by those encountered on the border, which is straining border security, immigration enforcement and courts, and other federal resources,” CBP Commissioner Kevin McAleenan said in a statement.

McAleenan is due to appear before the Senate Judiciary Committee for an oversight hearing on Tuesday amid criticism over his agency’s practice of limiting the number of people allowed to approach U.S. border crossings to request asylum.

McAleenan and Homeland Security Secretary Kirstjen Nielsen have urged migrants who wish to apply for asylum to approach the ports of entry and enter the country legally, but the numbers CBP provided Monday suggest the government is unable to handle applicants who follow the law.

In Tijuana, where caravans of Central American migrants have arrived in recent weeks hoping to enter the United States, thousands of asylum seekers are on a list waiting for the opportunity to lodge a fear claim and initiate the asylum process.

“The ports of entry were never designed or never built to hold large number of undocumented individuals, especially if they’re all arriving at one time,” said a CBP official, whose agency insisted during a media call that its officials must remain anonymous to share information.

CBP officers at the ports of entry have multiple responsibilities, the official said. “We must prioritize our personnel resources to address our counterterrorism mission, the narcotics interdiction efforts, our economic security mission in terms of trade enforcement and, of course, we must facilitate lawful trade and travel,” said the official, justifying the agency’s practices of what he called “queue management.”