WASHINGTON -- The head of Immigration and Customs Enforcement said efforts to deport families with orders to leave the country will continue after an upcoming national sweep that President Donald Trump said would start Sunday.

Matthew Albence, the agency's acting director, said targets were on an "accelerated docket" of immigration court cases for predominantly Central Americans who recently arrived at the U.S. border in unprecedented numbers. Similar operations occurred in 2016 under President Barack Obama and in 2017 under Trump.

"This family operation is nothing new," Albence told The Associated Press. "It's part of our day-to-day operations. We're trying to surge some additional resources to deal with this glut of cases that came out of the accelerated docket, but after this operation is over, these cases are still going to be viable cases that we'll be out there investigating and pursuing."

The operation will target people with final deportation orders on 10 major court dockets, including Chicago, Los Angeles, New York and Miami. Albence said that doesn't mean arrests will be limited to certain areas. Authorities will go where their investigations lead, even if it's five states away from where the case is filed.

Trump said authorities were "focused on criminals as much as we can before we do anything else."

"It starts on Sunday and they're going to take people out and they're going to bring them back to their countries or they're going to take criminals out, put them in prison, or put them in prison in the countries they came from."

The operation further inflamed the political debate over immigration as Trump appeals to his base with a pledge to crack down on migrants and Democrats cast the president and his administration as inhumane for going after families.

The Obama-era family operation in 2016 resulted in about 10% of those targeted being arrested, and the2017 effort had a lower arrest rate, Albence said. Other operations that have targeted people with criminal arrest records have yielded arrests rates of about 30%, aided by access to law enforcement databases.

"If you have an individual that's been arrested for a criminal violation, you're going to have much more of an investigative footprint," Albence said.

Administration officials have said they are targeting about 2,000 people, which would yield about 200 arrests based on previous crackdowns. Trump has said on Twitter that his agents plan to arrest millions of immigrants in the country illegally.

It is highly unusual to announce an enforcement sting before it begins. The president postponed the effort once before after a phone call with House Speaker Nancy Pelosi, but immigration officials said it was also due in part to law enforcement concerns over officer safety because details had leaked.

But they're pressing ahead with this one, even though the president and other administration officials have discussed the long-planned family operation for months.

"Nothing to be secret about," Trump said. "If the word gets out, it gets out because hundreds of people know about it."

The operation will target entire families that have been ordered removed, but some family may be separated if some members are in the country legally. Albence gave a hypothetical example of a father and child in the U.S. illegally but a mother who isn't

"If the mother wants to return voluntarily on her own with the family, she'll have an opportunity to do so," he said.

Families may be temporarily housed in hotels until they can be transferred to a detention centre or deported. Marriott said it would not allow ICE to use its hotels for holding immigrants.

If ICE runs out of space, it may be forced to separate some family members, Albence said. The government has limited space in its family detention centres in Texas and Pennsylvania.

"If hotels or other places do not want to allow us to utilize that, it's almost forcing us into a situation where we're going to have to take one of the parents and put them in custody and separate them from the rest of their families," he said.

Meanwhile, activists ramped up efforts to prepare by circulating information about hotlines and planning public demonstrations. Vigils outside of detention centres and hundreds of other locations nationwide were set for Friday evening, to be followed by protests Saturday in Miami and Chicago.

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Spagat reported from San Diego.