The Trump administration’s immigration crackdown is under way today - targeting migrant families in major cities across the country.

Sweeps had been expected to start on Sunday, but New York City mayor Bill de Blasio tweeted on Saturday that the Immigration and Customs Enforcement (ICE) agency had already taken action in New York.

He said they had targeted Brooklyn’s Sunset Park and parts of Harlem, but had been unsuccessful in detaining anyone. He says he has refused too co-operate with ICE.

Immigrant communities have been on edge since President Donald Trump's administration announced plans for the operation, with some going to extreme lengths to avoid being deported.

There were reports of some families stockpiling food and drawing the curtains, while others pinned notices to the inside of their front doors with legal advice on what to do if enforcement agents came knocking.

‘Families belong together’ protests over Trump immigration policy Show all 8 1 /8 ‘Families belong together’ protests over Trump immigration policy ‘Families belong together’ protests over Trump immigration policy Mishawaka, Indiana AP ‘Families belong together’ protests over Trump immigration policy Washington DC AFP/Getty Images ‘Families belong together’ protests over Trump immigration policy New York Mayor Bill De Blasio speaks in Tornillo, Texas alongside the many other US mayors who have called for detained immigrant children to be reunited with their families AP ‘Families belong together’ protests over Trump immigration policy Albuquerque Mayor Tim Kelle leaves a teddy bear as a gift for detained immigrant children in Tornillo, Texas AP ‘Families belong together’ protests over Trump immigration policy Seattle Mayor Jenny Durkan and Los Angeles Mayor Eric Garcetti leave sandals as gifts for detained immigrant children in Tornillo, Texas AP ‘Families belong together’ protests over Trump immigration policy San Diego, California EPA ‘Families belong together’ protests over Trump immigration policy US embassy, Mexico City AFP/Getty Images ‘Families belong together’ protests over Trump immigration policy San Diego, California EPA

Immigrants who've been given orders to leave the country are government targets in at least 10 cities.

Advocates are coaching them on their rights, including instructions not to respond if agents knock on the door unless shown a warrant signed by a judge.

Independent Minds Events: get involved in the news agenda

The American Civil Liberties Union filed a pre-emptive lawsuit Thursday that aims to protect asylum seekers. Activists held demonstrations and advocates coached immigrants on their rights.