"President Trump’s family separation policy leaves a dark stain on our nation," Pelosi stated. "Ripping vulnerable little children away from their parents is an utter atrocity that debases America’s values and our legacy as a beacon of hope, opportunity and freedom.
Pelosi also called the policy barbaric and a violation constitutional protections that apply to illegal border crossers as well as US citizens and residents.
More than 2,000 children have been separated from parents, who entered the US illegally, according to US officials. The policy does not apply to immigrant families who enter at established border crossings and apply for political asylum.
The Trump administration's immigration policy has come under fire from Republicans and Democrat, as well as religious leaders who have been strong defenders of the president.
"Longstanding US Supreme Court precedents protect parental rights and family integrity, and make clear that the separation and long-term detention of children is illegal," Pelosi said. "For the President to allege that there is a law or precedent for severing parents and children is simply a falsehood. For him to blame Democrats is yet another sign of his pathological need to distract and divert attention for his constant trampling over the law."
Pelosi said on Monday that protecting children and families is about basic morality and common decency.
"We hope that President Trump will remember his obligations – as a father, elected official and American – and immediately rescind this barbarous policy," Pelosi said.
In April, US Attorney General Jeff Sessions announced a zero-tolerance policy of dealing with families crossing the border, which included separating children from parents, to deter illegal immigration.
The US Department of Homeland Security has said nearly 2,000 immigrant children were separated from their parents during apprehensions from April 19 through May 31.