Immigration officials are planning a fresh round of deportation raids targeting hundreds of Central American families who entered the U.S. illegally, according to a published report. 

Reuters reported Thursday that Immigration and Customs Enforcement (ICE) has told field offices to make a 30-day arrest "surge" against mothers and children who have already been told to leave the country. Reuters also reported that the operation would target those who entered the U.S. as minors and have since turned 18. 

The exact dates of the deportation raids were not immediately clear, but Reuters reported that they were expected to last through next month. 

The planned raids come four months after a two-day operation that resulted in the detention of 121 people. Those raids focused on Texas, Georgia and North Carolina. It was not immediately clear where the latest raids would take place.

The operations are the latest effort to deter illegal immigrants from flooding the U.S.-Mexico border and straining federal resources, as happened in the summer of 2014. According to the latest Customs and Border Protection (CBP) figures, agents detained 27,754 unaccompanied minors from Central America in the first six months of Fiscal Year 2016 (ending in March), almost double last year's total of 15,616 and just shy of the 2014 record of 28,579.

The numbers for immigrants traveling as families (defined as at least one parent and one child) is even higher, with 32,117 apprehended -- almost triple last year's total of 13,913 and well above the 2014 “surge” figure of 19,830.

Both Democratic presidential candidates expressed opposition to the planned raids Tuesday, with front-runner Hillary Clinton saying they are "not productive and do not reflect who we are as a country."

"Families fleeing violence in Central America must be given a full opportunity to seek relief," Clinton added. "And we need to take special care of children."

Vermont Sen. Bernie Sanders issued a statement calling the raids "painful and inhumane" while asking President Obama to give Central American families temporary protective status through an executive order.

"Sending these people back into harm’s way is wrong," Sanders said.

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