New York City Mayor Bill de Blasio said that he was surprised to find out his city has hosted 239 immigrant children separated at the US-Mexico border on Wednesday, saying that the federal government "on purpose" did not provide this information.

Holding a press conference in front of Cayuga centre, an agency that serves as a day care centre for children and places them in foster homes.

"The youngest to come here, they told us was nine-months-old. So we're talking about children in some cases who literally can't even communicate, have no idea what's happening to them, no ability to be in touch with their families," de Blasio told reporters.

US President Donald Trump backed down on Wednesday on the immigration policy that sparked outrage at home and abroad, signing an executive order to end the separation of children from their parents when immigrant families are caught crossing the US-Mexico border illegally.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.