Vice President Mike Pence has attacked Democrats for calling for the abolition of Immigration and Customs Enforcement (ICE) amid weeks of outcry about the country's treatment of migrants, claiming the Trump administration would "never abolish ICE".

Speaking at the agency's headquarters on Friday, Mr Pence declared that President Donald Trump is "100 per cent" behind the agency.

"The calls for abolishing ICE are not only outrageous, they are irresponsible,” the vice president said, adding: “We will always stand proudly with our brave heroes of ICE and the Border Patrol."

Mr Pence singled out Democratic politicians such as Senators Elizabeth Warren and Kamala Harris, as well as New York Mayor Bill de Blasio, who have all supported calls to dismantle the agency.

"The truth is that opposition of ICE has moved to the centre of the Democratic Party itself, just when you thought the Democrats couldn't move farther to the left," Mr Pence said.

Calls to abolish ICE have grown in recent weeks, as reports surfaced about the treatment of migrants in US custody.

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More than 2,000 migrant children were separated from their families at the border this year under a new, Trump-administration “zero tolerance” policy. Mr Trump effectively ended the policy last month – with an executive order requiring families to be detained together – but the move failed to quell backlash.

Nineteen agents in charge at ICE’s Homeland Security Investigations unit wrote a letter to Secretary Kirstjen Nielsen last week, asking to be distanced from the agency. At least 10 US politicians have also come out in favour of abolishing ICE – a 20,000-person body created in the aftermath of 9/11 as part of the new Homeland Security Department.

"The President's deeply immoral actions have made it obvious that we need to rebuild our immigration system from top to bottom, starting by replacing ICE with something that reflects our values," Ms Warren wrote in a Facebook post on Saturday.

Woman lies in front of immigration enforcement van in Chinatown

Mr Trump, meanwhile, has doubled down on his support of the agency, tweeting on Thursday that he would not stand for the “vile Democrat smears in law enforcement”.

“We will always stand proudly with the BRAVE HEROES of ICE and BORDER PATROL!” he added.

That same day, the White House sent a fact sheet to reporters entitled “Abolishing Ice Would Erase America’s Borders And Open The Floodgates To More Crime, Drugs, And Terrorism”.