Washington, Sep 10 : South Korea's Foreign Minister Cho Hyun vowed Wednesday to "rescue" South Koreans detained in a recent US immigration crackdown "within the shortest time," as his ministry cited "unspecified U.S. circumstances" as the reason for a delay in their release from a detention center in Georgia.

Cho's remarks came as he is set to meet US Secretary of State Marco Rubio at the White House to discuss a range of issues concerning the detainees, Yonhap News Agency reported. They were initially scheduled to meet Tuesday, but their talks were rescheduled for Wednesday.

"(We) will ensure whatever it takes ... in the best way that our citizens will be rescued and be able to board a (chartered) plane within the shortest time," Cho told reporters.

Asked to elaborate on the US circumstances that led to a delay in the Koreans' release, Cho said, "We are not at a stage to tell you about that."

More than 300 South Korean workers were initially set to board a chartered flight Wednesday at an airport in Atlanta to return home, six days after their arrest in an immigration raid at an electric vehicle battery plant construction site for a joint venture of Hyundai Motor Group and LG Energy Solution in Bryan County near Savannah.

A total of 475 people, including some 300 Koreans, were arrested in the raid, which US authorities dubbed as the "largest single site enforcement operation in the history of Homeland Security Investigations."

US officials said those arrested were found to be working illegally in the United States, including those on short-term or recreational visas that bar them from working.

On Tuesday, South Korean President Lee Jae Myung said he feels heavy responsibility over the detention of South Korean workers at a battery plant construction site in Georgia by US immigration authorities, offering his deep sympathy.

Lee made the remarks at a Cabinet meeting as more than 300 South Koreans have been taken into custody at a detention center in Georgia following a recent raid by US immigration authorities on the electric battery plant construction site by Hyundai Motor Group and LG Energy Solution.

Lee told the meeting that he felt a "heavy sense of responsibility" as the president who is tasked with ensuring the safety of the people.

"Our citizens who were detained by US immigration authorities are expected to return home soon," Lee said. "I offer my deepest sympathy for the shock and distress they must have felt from this sudden incident."

"I hope that no unfair infringements on the activities of our people and businesses -- which contribute to the shared development of both Korea and the United States -- will ever happen again," he said.

Kim Yong-beom, presidential chief of staff for policy, said the government conveyed strong regret to the US government over the detention of South Korean workers.

Kim told a debate session with broadcasting journalists that Seoul officials are finalizing administrative procedures to allow the detained Koreans to return home under "voluntary departure" rather than "deportation."

Kim noted that efforts to ease visa hurdles for Korean workers over the past decade have made little progress amid growing anti-immigration sentiment in the US, stressing the need to revise visa rules in consultation with Washington to support Korean companies' investment in the US.

"If necessary, the presidential office and the White House should establish a working group to find a short-term solution and push for legislative changes in the longer term," he said.

/IANS