Washington, July 1 (IANS): Thousands of people gathered here on Saturday outside the White House to demand that US President Donald Trump's administration immediate reunify the families of mostly undocumented migrants who have been separated as a result of its policies.

Singer Alicia Keys, actress America Ferrera and playwright Lin-Manuel Miranda led a rally in Lafayette Square that, according to organizers, drew more than 30,000 people to downtown Washington, Efe reported.

Similar marches were held in 750 other cities throughout the US.

"This fight does not belong to one group of people, one color of people, one race of people, one gender - it belongs to all of us," Ferrera, best-known for her role in the 2006-2010 US television comedy/drama "Ugly Betty," said.

The demonstrators, rallying under the slogan "Families Belong Together," demanded that hundreds of mostly Central American migrant children be immediately reunified with their parents.

More than 2,300 children have been separated from their parents and placed in Health and Human Services shelters under Trump's "zero tolerance" policy, which mandates criminal charges against people who illegally cross the southern border.

The President signed an executive order earlier this month to stop family separation, but the youngsters already sent to shelters remain there and in many cases the parents have no knowledge of their kids' whereabouts.

The administration, meanwhile, has filed a motion with a federal district court in California asking for modification of a 1997 accord between the government and immigrants' rights groups that limited to 20 days the length of time that migrant children can be detained.

Trump's team sees the Flores Settlement, as the agreement is known, as an obstacle to its program to end family separation, which includes the idea of keeping the kids together with their parents in detention centers.

Family separation at the border has spurred protests across the United States, notably at Border Patrol and detention facilities and at offices of US Immigration and Customs Enforcement.