South Korea is moving to pick up Korean workers following a raid in the U.S. state of Georgia last week, a Korean presidential official said on Sunday, as the Trump administration has promised more raids on businesses.

The negotiations to release about 300 South Koreans who were detained have concluded, and processing for their release from custody is ongoing, according to South Korea's presidential office, which issued a statement late on Sunday.

A chartered plane will be flown to the U.S. to take them back to South Korea as soon as the processing by the two countries is complete, the office said in a statement. It did not provide details about what administrative steps are being taken.

Representatives for the Department of Homeland Security (DHS) did not respond to a request for comment. Meanwhile, White House border czar Tom Homan separately has vowed to expand immigration raids on workplaces.

Later on Sunday, U.S. President Donald Trump sounded more conciliatory while still driving home a vow to enforce tough immigration policy, calling on foreign companies investing in the U.S. to "respect our nation's immigration laws."

The arrests in Georgia followed tougher rhetoric by Trump on illegal immigration. For weeks, Trump and his top officials have suggested the administration could send National Guard troops and federal officers to Chicago to target crime and immigration.

Trump campaigned on making immigration a pillar of his administration and has moved to ramp up deportations nationwide since taking office in January.

Visa concerns amid trade talks

South Korea's presidential chief of staff, Kang Hoon-sik, said on Sunday that the government will seek ways to improve the visa system for Korean workers traveling to the U.S. to "prevent a similar incident."

DHS has said the arrested workers have been barred from working in the U.S. after crossing the border illegally or overstaying visas.

Relations between Washington and Seoul, a key U.S. ally and investor, remain fraught, as both sides seek to hammer out final details of their trade deal announced in July.

Trump stated on Sunday that the U.S. and South Korea have a great relationship and that the Hyundai plant issue will not strain the bilateral relationship.

LG Energy Solution has suspended staff business trips to the U.S., except for certain exceptional cases, and will be recalling those employees now in the U.S.

Trump may visit South Korea in October for the Asia-Pacific Economic Cooperation summit, Reuters reported.

(With input from agencies)