A demonstrator dressed as US President Donald Trump marches as immigration activists rally as part of a march calling for "an end to family detention" and in opposition to the immigration policies of the Trump administration, in Washington. Picture: Jonathan Ernst/Reuters

Washington - Hundreds of protests are scheduled to take place on Saturday in cities across the United States against President Donald Trump's hardline immigration policies, with a focus on the separation of families, a hot-button topic that has drawn public ire.

The protests are expected to draw hundreds of thousands of people.

"No child should be locked in a cage. Let's end family detention and reunite kids with their families," the organizer, Families Belong Together coalition, said.

More than 2,000 children have been split from their parents at the US-Mexico border in recent weeks, as the federal government launched tougher enforcement to deter migration. Trump has since backtracked on the policy to separate families, though many remain divided.

A main event is scheduled to start at 11 am (1500 GMT) in the capital, Washington DC, where on Thursday hundreds of women were arrested as they protested inside the Congress. The demonstrators were later released.

Immigration activists rally in Washington as part of a march calling for "an end to family detention" and in opposition to the immigration policies of the Trump administration. Picture: Jonathan Ernst/Reuters

Several key lawmakers from the opposition Democratic Party have backed the demonstrators.

Trump, who was elected to office in 2016, ran his campaign in part promising to get tough on immigration, especially from the Middle East and Latin America.

He regularly links violent crime to migration, in an echo of populist rhetoric from far-right parties in Europe. The president says he is simply enforcing the law and trying to bring order to the system.

Protesters are increasingly demanding the federal government disband Immigration and Customs Enforcement (ICE), the agency which carries out much of the federal government's policies and is accused of having a heavy hand.