Washington - Thousands of demonstrators, baking in the heat and boiling mad against US immigration policy, marched across the country Saturday to protest the separation of families under President Donald Trump’s hardline policy.

Dubbed “Families Belong Together,” the demonstration in Washington began at Lafayette Square where crowds gathered directly across from the White House before a planned march toward the Capitol.

In New York, families, young people, children and the elderly - both recent arrivals and long-time citizens - all stood under a burning sun as part of a protest which a police officer said already numbered “a couple of thousand.”

“Say it loud, say it clear, refugees are welcome here,” they chanted, also declaring a welcome for Muslims.

A band of drummers whipped up the fervor of a crowd carrying signs including, “Our New York is Immigrant New York,” and “No Cages, No Ban, No Wall.”

“Abolish ICE,” said another sign, reflecting growing calls by activists for abolition of the country’s frontline immigration enforcement agency.

Starting in early May, in an attempt to staunch the flow of tens of thousands of migrants to the southern US border every month, Trump ordered the arrest of adults crossing the boundary illegally, including those seeking asylum. Many trying to cross the US-Mexico frontier are destitute people fleeing gang violence and other turmoil in Central America.

As a result of Trump’s crackdown, distraught children were separated from their families and, according to widely broadcast pictures, held in chain-link enclosures, a practice that sparked domestic and global outrage. Trump later signed an order ending the separation of families but immigration lawyers say the process of reuniting children and their parents will be long and chaotic.

About 2,000 children remain split from their parents, according to official figures released last weekend.

Saturday’s protests also come after the US Supreme Court on Tuesday handed Trump a major victory by upholding his ban that mostly applied to travelers from five primarily Muslim nations.

Julia Lam, 58, joined the New York protest with two friends and their young children in strollers.

Lam is a mother and a retired fashion designer who emigrated from Hong Kong in the 1980s.

“I think it’s really cruel to separate kids,” she said. “I am angry. I’m very sad already with what is going on with our country. I just don’t see how a human being would do such a thing.”

Courtney Malloy, 34, a lawyer, said it was important to show support for immigrants and that administration policies are “not America.”

“This is not what we stand for and this is not OK, and we will not stand here and watch our country be torn apart and watch babies be torn from their mothers,” she told AFP, holding a sign that said, “The Only Baby Who Belongs in a Cage is Donald Trump.”

More than 500 women, including a member of Congress, were arrested Thursday in the US Capitol complex protesting Trump’s immigration policy. Saturday’s demonstrations were expected to be the biggest yet. Trump has made fighting immigration - both illegal and legal - a major plank of his “America First” policy agenda.

The Immigration and Customs Enforcement agency (ICE) makes arrests and otherwise enforces the administration’s immigration crackdown, but an emerging coalition of politicians, activists and pro-immigrant protesters has begun calling for the dismantling of ICE.

Critics say the agency has treated some would-be immigrants cruelly and unfairly. “Occupy ICE” camps have been set up in several US states. One of the first voices to call for the abolition of ICE was New York Democratic gubernatorial candidate Cynthia Nixon. She has since been joined by New York Mayor Bill de Blasio, who told radio station WYNC, “You need some kind of agency to deal with immigration, but ICE is not that”; and by Senator Kirsten Gillibrand, also of New York, who in a tweet called ICE “a cruel deportation force.”

On Saturday morning Trump tweeted support for ICE, saying “radical left Dems want you out. Next it will be all police. Zero chance, it will never happen!”

The political backlash against ICE is so intense that members of the agency’s criminal investigative division have asked Homeland Security Secretary Kirstjen Nielsen to split them off as a separate agency, The Washington Post reported on Thursday.