Federal agents have descended on the city of Charlotte in North Carolina as part of US President Donald Trump's crackdown on illegal immigration, the Department of Homeland Security (DHS) has said.

Federal immigration authorities carried out nearly 100 arrests in the Charlotte area on Saturday, according to CBS, the BBC's American news partner.

Local officials, including Mayor of Charlotte Vi Lyles, released a joint statement criticising the operation, saying it was causing unnecessary fear and uncertainty in the community.

Since Trump's return to office, he has deployed troops to Washington DC, Los Angeles, and Chicago to deliver on his promise of the largest deportation programme in US history.

The DHS announced Operation Charlotte's Web on Saturday, saying criminal illegal aliens would be targeted in the Democratic-run city.

We are surging DHS law enforcement to Charlotte to ensure Americans are safe and public safety threats are removed, DHS Assistant Secretary Tricia McLaughlin said.

Armoured vehicles and special operations teams could be involved in the North Charlotte crackdown, according to internal government documents seen by the BBC's US partner, CBS News.

Several church members doing yard work at a church in east Charlotte fled into woods when agents arrived and detained one man, The Charlotte Observer reported, quoting the church's pastor.

We thought church was safe and nothing [was] gonna happen, a 15-year-old witness told the newspaper.

Officials said there are a number of organisations standing ready to assist individuals seeking legal guidance on immigration matters.

The DHS said they are carrying out the operation because North Carolina has not honoured the nearly 1,400 Immigration and Customs Enforcement (ICE) detainees - meaning they had been released due to sanctuary policies.

Charlotte is not a sanctuary city - cities that have policies in place to limit the assistance given to federal immigration authorities - but it is a certified welcoming city. This is a formal designation for cities that are committed to immigration inclusion.

President Trump and Secretary [Kristi] Noem will step up to protect Americans when sanctuary politicians won't, the DHS said.

Charlotte is an ethnically diverse city, with about 17% of residents being born outside of the country, according to Data US.

DHS has not said how long the raids will last. Chicago's crackdown, which began in September, is still ongoing.

Earlier in the week, US Representative and Democrat, Alma Adams, expressed concern about Border Patrol and ICE agents coming to North Carolina.

The next city on Trump's list is set to be New Orleans, according to CBS, with reports suggesting that as many as 200 agents could be deployed there. Operations in previous cities like Chicago and Los Angeles have come under fire over concerns of excessive use of force.