WASHINGTON - The US Department of Homeland Security (DHS) said Thursday it has suspended horse patrol in the Texas city of Del Rio that borders Mexico, a move that came amid public outrage over border patrol agents' hostile treatment of Haitian migrants.

"We have ceased the use of the horse patrol in Del Rio temporarily. We'll prioritize other methods for identifying individuals who might be in medical distress," CNN reported, citing a DHS official, who added that the agency is "working closely with the government of Mexico and our partners in US government to try to pull on that thread and see how we can enhance visibility into those organized movements."

Video footage and images showing mounted US Border Patrol officers at the Del Rio sector of the US-Mexico border apparently using their reins as whips against Haitian migrants to block their movement into the United States circulated earlier this week, stirring Democrats' condemnation of the agents' inhumane action as well as Republicans' accusation against the Joe Biden administration that it failed to secure the border.

The House Homeland Security Committee, which grilled DHS Secretary Alejandro Mayorkas on Wednesday during a hearing over the migration crisis, called the suspension of horse patrol a "good step", adding in a tweet that it was still "a minimum" move until the DHS completed its investigation into the incident.

Mayorkas told the panel that an undisclosed number of agents involved in the incident had been placed on administrative duty, meanwhile pledging that the probe would conclude within days.

US media cited DHS as saying in response to media inquiries over the ongoing expulsions that 12 repatriation flights had left the United States between Sunday and Wednesday, and that 1,401 Haitian nationals had been returned to Haiti. The flights would continue, it added.

Another 3,206 Haitians had been moved from the camp underneath the Del Rio International Bridge to US Customs and Border Protection custody or to other sectors, the DHS said. They would be either expelled via Title 42, which authorizes the expulsion of foreign nationals who have recently been in a country where a communicable disease is present, or placed into removal proceedings.

The agency said fewer than 5,000 migrants still remained at the camp, where rights activists said living conditions are harsh and some migrants are targets of excessive use of force by immigration enforcement agents.

Earlier on Thursday, US Special Envoy for Haiti Daniel Foote resigned in protest of what he called "the United States inhumane, counterproductive decision" to deport Haitian migrants to their home country. He was appointed to the position only in July in the wake of former Haitian President Jovenel Moise's assassination.