The US homeland security secretary, Alejandro Mayorkas, on Sunday defended the Biden administration’s decision to send thousands of Haitians to a home country they fled because of natural disasters and political turmoil.

Mayorkas told NBC’s Meet the Press the removals were justified because of the coronavirus pandemic, a point disputed by advocates and public health experts.

“The Centers for Disease Control [and Prevention, or CDC] has a Title 42 authority that we exercise to protect the migrants themselves, to protect the local communities, our personnel and the American public,” Mayorkas said.

“The pandemic is not behind us. Title 42 is a public health policy, not an immigration policy.”

Since Donald Trump’s administration implemented Title 42 in March 2020, advocates and dozens of public health experts have called for its end.

Under Title 42, people who attempt to cross the border are returned to Mexico or deported to their home countries without an opportunity to test asylum claims.

In January, Joe Biden stopped the rule from applying to children. Despite that, at least 22 babies and children were deported to Haiti in February.

More than 30 public health experts wrote to Mayorkas and the head of the CDC, Rochelle Walensky, earlier this month, saying Title 42 was “scientifically baseless and politically motivated”.

This coalition has repeatedly said the policy violates the right to seek asylum and ignores how basic public health measures can reduce the spread of Covid-19.

“Title 42 runs counter to the government’s own commitment to address Covid-19 globally,” the coalition said. “The absence of effective Covid-19 mitigation services at the border and the expulsion of people to situations in which they may be exposed to Covid-19 and unable to practice prevention are contrary to the US government commitment to address Covid-19 globally.”

On Sunday, Mayorkas told CNN about 4,000 Haitians who arrived in the past two weeks have been expelled, 13,000 others had been allowed to enter the US to pursue their immigration cases in court and 8,000 had voluntarily chosen to return to Mexico.

NBC’s Meet the Press host Chuck Todd questioned Mayorkas about why thousands were being sent to Haiti even though they had traveled to the US from South America.

“These are Haitian nationals,” Mayorkas said. “Some of them don’t have documents from the countries from which they just left. So they are subject to removal.”

Haitians have made dangerous journeys across South America for years, seeking safety and security because of devastating natural disasters and political instability in their home country.

The latest group to make the journey has received more attention than usual, after thousands gathered at a makeshift camp at the Del Rio border crossing between Texas and Mexico, prompting the US government to close the site.

At one point, US border patrol agents on horseback chased down migrants, actions which drew international scrutiny.

On Friday, Joe Biden said the agents concerned “will pay” for their actions. Mayorkas took a more muted position on CNN’s State of the Union on Sunday.

The secretary said he was “incredibly proud to work alongside” border patrol agents and would wait to see the outcome of an investigation into the use of horses at Del Rio.

“What those images suggest, what they appear to portray was horrifying and that I think that deserves attention,” Mayorkas said. “That is quite different from fact determinations.”

The Republican Texas governor, Greg Abbott, also defended the agents, telling Fox News Sunday he would hire them if they lost their jobs.

“If they are at risk of losing their job [under] a president who is abandoning his duty to secure the border, [they will] have a job in the state of Texas,” Abbott said.

The Del Rio encampment was cleared on Friday and officials planned to re-open the border crossing on Monday.

Abbot, however, said Texas would implement its own immigration policies, including building a wall.

“Secretary Mayorkas and, if I can be candid, even President Biden, they are in dereliction of duty,” he said.

Mayorkas said the US government continued to expel people to Haiti after determining they could be sent there safely. The people being returned were not being tested for Covid-19, he said.

The US envoy to Haiti, Daniel Foote, resigned last week in protest at what he called the Biden administration’s “inhumane” mass deportation of Haitian migrants and asylum seekers to their home country.

Haiti, he said, was a highly dangerous “collapsed state”.