(CNN) - The US has returned around 6,000 asylum seekers to Mexico while they await their immigration proceedings, the Department of Homeland Security told CNN on Tuesday.
The individuals have been returned under the Migrant Protection Protocols policy, informally known as Remain in Mexico, that requires some asylum seekers to wait in Mexico until their immigration hearing.
The number of migrants falling under the policy appears to be doubling over time. On May 9, around 3,700 individuals had been returned to Mexico until their immigration hearing. In late April, the number was more than 1,600 migrants.
The policy was initially rolled out at the San Ysidro port of entry in January. It's since expanded elsewhere in California, New Mexico and Texas.
Like other administration immigration policies, however, it has also been challenged in court. The policy has drawn opposition from immigrant advocates and lawyers who argue that it puts migrants who are predominantly from Northern Triangle countries and seeking asylum in the US in harm's way.
Earlier this month, a federal appeals court allowed the Trump administration to continue returning some asylum seekers to Mexico for the time being.
A panel of the 9th US Circuit Court of Appeals, while split on some issues, listed a number of factors that went into the decision, including risk of injury in Mexico and negotiations between the US and Mexico.
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