By Agencies

US officials say 1,995 minors separated from parents or legal guardians over six weeks under sharply criticised policy.

Almost 2,000 children have been separated from their parents or legal guardians at the US-Mexico border since a highly criticised "zero tolerance" immigration policy came into place, according to US officials. 

A Department of Homeland Security spokesman told reporters on Friday that 1,995 minors were separated from 1,940 adults who crossed the US border without documents between April 19 and May 31. 

The adults were held in preparation of prosecution for undocumented entry into the United States, immigration violations, or possible criminal conduct.

All cases of undocumented entry are being referred for criminal prosecution under the "zero tolerance" policy announced by Attorney General Jeff Sessions in May.

The separations are a consequence of this prosecution, as minors cannot be held with their parents or legal guardians. 

The policy has come under fire from politicians, immigration advocates and human rights groups.

Earlier this month, thousands of people rallied in cities across the US calling on US President Donald Trump to reverse the policy. 

The United Nations High Commissioner for Human Rights last week said the practice "amounts to arbitrary and unlawful interference in family life, and is a serious violation of the rights of the child". 

House Minority Leader Nancy Pelosi called the policy "shameful" and said there's no policy justification for it.

Reacting to the separations of nearly 2,000 children from their families, California Senator also urged the Trump administration to end "the immoral policy".

On Thursday, Sessions cited Christian scripture to justify detaining children separately from their fathers and said that, "Consistent, fair application of law is in itself a good and moral thing, and it protects the weak".

A day later, White House Press Secretary Sarah Sanders drew further anger and ridicule from many online after seemingly invoking the Bible to justify the Trump administration's policy.

Shortly after taking office, Trump signed an executive order, expanding the powers of the Immigration Customs Enforcement (ICE) agency to focus on detaining most undocumented immigrants, including those with no criminal record.

The number of interior removals - or deportations of those already in the US - grew by 37 percent during Trump's first year in office when compared with the same period in 2016, according to government data.

Sessions has also recently come under fire for issuing a ruling that may make it nearly impossible for domestic abuse and gang violence survivors to seek asylum in the US.