A medical worker collects samples for COVID-19 tests at a drive-thru site in Bogota, Colombia, May 14, 2020. (Photo by Jhon Paz/Xinhua)

"There was no kind of protection or (special) handling" and more than 80 fellow detainees "were not tested," said Carlos, 31, who fled San Salvador in January after gang members threatened to kill him for failing to pay protection money for his small business.

He said he had hoped to apply for asylum in the United States, but was caught almost immediately by border patrol agents and sent to the "icebox," a slang describing the frigid holding cells to keep detainees.

"I left El Salvador looking for a freer life in the United States, but in the hands of U.S. authorities I almost lost my life," he told Xinhua in a phone interview from a government-run shelter.

David Cruz, a 48-year-old Mexican migrant, said he was given a face mask and his temperature was checked when he was put in a holding cell in McAllen, Texas, but he was held with 27 others in "close, very close" quarters.

He was deported in May by taking one of eight flights designed to speed up the deportation process to Mexico, which is usually done by ground transport.

The objective of these flights is to reduce the spread of COVID-19 "to the United States," U.S. Customs and Border Patrol said in a statement.

However, Latin American experts said the U.S. move amid the COVID-19 outbreak might risk spreading the virus to the south of the United States, especially to the poor rural communities many migrants come from.

On May 4, international medical charity Doctors Without Borders urged the United States to suspend deportations, warning that the move could deteriorate situations in countries poorly equipped to deal with such crisis.

Loic Jaeger, the charity's director for Mexico and Central America, said earlier that deporting migrants without first checking for possible infection was a "criminal policy."