Raids to detain and deport migrants living in the US without permission are set to begin on the first full day of the new Trump administration, US media report.

The operations - threatened by Donald Trump?s ?border tsar? Tom Homan ? could begin in Chicago, a city with a large migrant population, as early as Tuesday, the New York Times and Wall Street Journal say.

Trump has said he will oversee the largest deportation programme in US history.

In an interview with Fox News this week, Homan promised a ?big raid? across the country. He has previously said Chicago will be ?ground zero? for the mass deportations.

The Immigration and Customs Enforcement (ICE) agency deports illegal migrants all the time. However, the operation it is expected to launch after Trump?s inauguration on Monday is expected to target so-called ?sanctuary? cities that limit co-operation with federal immigration officials.

Along with Chicago, New York City and Los Angeles are among the scores of US cities that have adopted ?sanctuary? policies.

?January 21st, you?re going to look for a lot of ICE agents in your city looking for criminals and gang members,? Homan told a Republican gathering in Chicago last month. ?Count on it. It will happen.?

New York, Los Angeles, Denver and Miami are also due to be targeted with raids, the Wall Street Journal reports, citing unnamed sources familiar with the plans.

Under Democratic President Joe Biden, ICE generally prioritised the arrest of illegal migrants who were serious criminals, had crossed the border recently or posed a national security threat.

While Trump?s team has signalled that it will begin with migrants who had committed crimes, all illegal migrants ? including those who have lived and worked in the US for many years and have no criminal history ? are more likely to be arrested and deported.

Immigration raids at construction sites where undocumented migrants are often employed are also expected to resume, after being discontinued by the Biden administration, according to CBS News, the BBC?s US partner.

Ahead of the expected hardening of US policy, more migrant farm workers have been seeking advice on dealing with immigration officials and assigning temporary guardians for their children.

?The administration is not yet sworn in, but people are already afraid,? Sarait Martinez, executive director of the Centro Binacional para el Desarrollo Ind?gena Oaxaque?o, which supports Mexican farm workers in California, told Reuters news agency.

As well as pledging to deport millions of illegal migrants and threatening workplace raids, some reports suggest that Trump could also do away with a longstanding policy that has made churches off-limits for ICE arrests.

However, the upcoming raids are likely to pose significant difficulties for officials ? with limited custody space to hold those detained.

At the same time, the Laken Riley Act ? named after a college student who was murdered last year in Georgia by a Venezuelan man previously arrested for shoplifting ? is expected to be passed by US lawmakers next week.

The proposed legislation will require the federal government to detain migrants living in the US illegally who are suspected of criminal activity ? even if they are not charged with any crime. (BBC)

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