Donald Trump sought to reinstate his controversial family separation policy, clashing with a now departing cabinet member over the issue, according to a new report.

The president’s calls to once again systematically separate migrant families — many of them arriving at the nation’s southern border legally while seeking asylum — reportedly put him at odds with Kirstjen Nielsen, the sixth secretary to the Department of Homeland Security.

The "collision" was first reported by NBC News on Monday.

The homeland security chief told Mr Trump the agency was unable to reinforce his policy as it defied federal court orders prohibiting the measure, multiple sources told the outlet.

Moreover, Ms Nielsen reportedly reminded the president he would be overturning his own executive order, which he signed to end the separation of migrant families after widespread backlash spilled over into nationwide protests and major demonstrations on Capitol Hill.

Undocumented immigration across the US-Mexico border Show all 14 1 /14 Undocumented immigration across the US-Mexico border Undocumented immigration across the US-Mexico border Immigrant children, many of whom are separated form their parents, are housed in Texas' tent city Reuters Undocumented immigration across the US-Mexico border A two-year-old Honduran asylum seeker cries as her mother is searched and detained near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Undocumented migrants ride on the top of a freight train referred to as the beast, or La Bestia Getty Undocumented immigration across the US-Mexico border A cage inside a US Customs and Border Protection detention facility in Texas Reuters Undocumented immigration across the US-Mexico border US Border Patrol Academy All new agents must complete a months-long training course at the New Mexico facility before assuming their posts at Border Patrol stations, mostly along the US-Mexico border Getty Undocumented immigration across the US-Mexico border US-Mexico border fence A group of young men walk along the Mexican side of the US-Mexico border fence in a remote area of the Sonoran Desert Getty Undocumented immigration across the US-Mexico border US-Mexico border fence in the US Man looks through US-Mexico border fence into the US in Tijuana, Mexico Getty Undocumented immigration across the US-Mexico border US-Mexico border fence US Border Patrol agent Sal De Leon stands near a section of the US-Mexico border fence while stopping on patrol on in La Joya, Texas Getty Undocumented immigration across the US-Mexico border US Border Patrol Academy US Border Patrol instructor yells at trainees after their initial arrival to the academy Getty Undocumented immigration across the US-Mexico border Memorial service in Guatemala Families attend a memorial service for two boys who were kidnapped and killed in San Juan Sacatepequez, Guatemala. Crime drives emigration from Guatemala to the United States, as families seek refuge from the danger Getty Undocumented immigration across the US-Mexico border Arrests on the border Undocumented immigrants comfort each other after being caught by Border Patrol agents near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Detention holding facility A boy from Honduras watches a movie at a detention facility run by the US Border Patrol Getty Undocumented immigration across the US-Mexico border Mexican farm workers Mexican migrant workers harvest organic parsley at Grant Family Farms in Wellington, Colorado Getty Undocumented immigration across the US-Mexico border Mexican family in Arizona A Mexican immigrant family sits in the living room of their rented home in Tuscon, Arizona. The family that Arizona's new tough immigrant law had created a climate of fear in the immigrant community. Getty

Ms Nielsen, who was expected to stay on as the head of the agency until Wednesday, oversaw the implementation of the zero tolerance policy and defended the Department of Homeland Security under Mr Trump when grilled on Capitol Hill last year.

She has repeatedly denied the administration ever separated families at the border, despite public evidence, Congressional hearings and press reporting all indicating families were in fact separated under her watch. “We do not have a policy of separating families at the border,” she wrote in June 2018, adding, “Period.”

The secretary released a statement on Sunday saying it was a “great honour” to serve in the role.

“Despite our progress in reforming Homeland Security for a new age, I have determined that it is the right time for me to step aside,” she wrote.

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Ms Nielsen added, “I hope that the next Secretary will have the support of Congress and the courts to fully secure America’s borders and which have contributed to discord in our nation’s discourse.”