More than 5,000 Central American asylum seekers have been returned to Mexico under the Trump administration's controversial "Remain in Mexico" policy, a Mexican government official told CBS News on Monday. The policy is aimed at deterring an unprecedented flow of migrant families heading to the southwestern border.

As of this week, 5,273 migrants from Guatemala, Honduras and El Salvador — collectively known as the "Northern Triangle" — have been returned to Mexico to await their court hearing in the U.S., the official said. A federal U.S. appellate court has allowed the administration to continue implementing "Remain in Mexico" while it reviews a legal challenge to the practice, which immigrant advocates believe puts migrants at risk.

The Mexican official said the American policy is creating an unsustainable situation for the country's government, led by leftist President Andrés Manuel López Obrador. Still, the official said the Mexican government will continue to prioritize the safety of migrants.

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"It has many implications," the official added, referring to the "Remain in Mexico" policy. "However, with the new immigration policy, all the tools we have to apply to safeguard the physical and moral integrity of foreigners must be applied, regardless of condition or nationality."

The Department of Homeland Security, which oversees the implementation of the policy, told CBS News last week that it had returned 3,700 asylum seekers to Mexico. The agency did not immediately respond to inquiries about the apparent discrepancy between its tally and that of the Mexican government.