The U.S. Border Patrol chief testified Thursday that migrants from 52 countries have illegally crossed the border this year as she described an agency “overwhelmed on a daily basis” by the escalating crisis.

“While smugglers primarily target the Northern Triangle, family units from 52 countries have illegally crossed the southern border so far this year,” U.S. Border Patrol Chief Carla Provost told the House Homeland Security Border Security, Facilitation and Operations Subcommittee.

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Her testimony points to the increasingly international nature of the migrant flows crashing against the U.S. border, further complicating efforts to remove those without valid asylum claims. Provost told lawmakers that the numbers from Africa have also increased.

“In just two weeks, more than 740 individuals from African nations – primarily family units -- have been apprehended in Del Rio sector alone, compared to only 108 who crossed the southern border in the first eight months of the fiscal year,” she said.

She went on to say that families from countries such as Brazil, Nicaragua, Ecuador, Peru, Romania and Vietnam are taking the same pathways as migrants from Central America and taking advantage of legal loopholes in the U.S. system. In April, Rio Grande Valley Sector Chief Patrol Agent Rodolfo Karisch told Senate lawmakers that his sector had apprehended people from countries including China, Bangladesh, Turkey and Egypt.

The Trump administration has been calling on both Congress and Mexico to do more to tackle the migrant crisis. President Trump announced this month he had secured a deal with Mexico that would see the U.S. expand its policy of returning asylum applicants to Mexico while claims are processed.

A Senate panel on Wednesday approved a $4.6 billion request for funding to tackle the humanitarian crisis at the border, but only after including a condition that none of the money be used for a border wall.

Earlier in her remarks, Provost said that she has had to move 40-60 percent of manpower away from the border to process and care for nearly 435,000 families and children who have traveled across the border this year.

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She said they are struggling to cope with large groups of migrants of more than 100 at a time that are traveling to the border at once.

“With 193 of these large groups so far this year, our operations are now being overwhelmed on a daily basis,” she said.

Later, during questioning from Rep. Michael Guest, R-Miss., she said that drug smugglers are “taking advantage” of the chaos at the border to funnel narcotics into the U.S.

“They’ll run a large group of people and then while my agents are distracted dealing with that, they’re running narcotics in other areas and this is a tactic that they use,” she said.

The testimony came as Fox News reported that hundreds of illegal immigrants attempting the cross the border as part of the massive migrant caravans were found to have criminal histories in the U.S.

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Department of Homeland Security documents provided to House Oversight Committee Republicans included internal data showing more than 1,000 migrants traveling as part of caravans to the border within the past nine months had “U.S. criminal histories” and hundreds had “U.S. criminal convictions.”

The files detailed one migrant caravan of nearly 8,000 individuals that started toward the border in October 2018 and arrived south of California by December. According to U.S. Immigration and Customs Enforcement (ICE), 660 of them had U.S. criminal convictions—with 40 convicted of assault or aggravated assault with a deadly weapon, and three convicted of murder.

Fox News’ Brooke Singman contributed to this report.