WASHINGTON, Sept. 11 (Xinhua) -- U.S. immigration authorities detained more than 300 South Korean workers at a battery plant in Georgia last week during a criminal investigation into visa violations, sparking strong reactions from South Korea and raising concerns about the future of foreign investment in the United States.

South Korean President Lee Jae-myung, who just visited the United States and held talks with U.S. President Donald Trump in late August, called the incident an "unjust infringement" and stated that he feels "a heavy sense of responsibility" for protecting South Korean nationals.

In response, Seoul sent Foreign Minister Cho Hyun to Washington. On Wednesday, Cho met with U.S. Secretary of State Marco Rubio to discuss the detained workers and urged U.S. authorities to ensure their quick return without any disadvantage for future reentry.

A chartered Korean Air flight arranged to bring the detained workers home arrived at an airport in Atlanta on Wednesday. According to Yonhap, the plane is set to leave on Thursday with 316 South Koreans on board.

U.S. officials defended the operation, describing its aim as enforcing immigration laws. They said that most of the detainees had entered the United States on B-1 visas or ESTA, which do not permit employment. Giving no comment on the Georgia operation, White House border czar Tom Homan vowed more worksite enforcement operations.

Hyundai and LG Energy Solution, the owner of the targeted site, clarified that the detained workers were subcontracted technicians on temporary assignments. In a statement on the raid, Hyundai pledged to comply fully with U.S. immigration laws and regulations.

Referring to the detainees as "illegal aliens" in an interview, Trump emphasized on social media that America remains open to foreign investment, as long as companies comply with U.S. immigration regulations.

However, when explaining the one-day delay of the detainees' repatriation on Wednesday, Rubio said Trump "encouraged" those workers to stay in the United States to continue their work and train locally hired workers, according to Yonhap.

The targeted plant is part of Hyundai's 12.6-billion-dollar project in Georgia, which is described as "the largest single investment in the state's history" and plans to eventually employ 8,500 people. The raid may slow down its construction. LG Energy Solution has stopped all business travel for its employees to the United States unless indispensable, according to media reports.

Analysts warned that the raid could deter foreign companies from investing in the United States. The scale of foreign investment in U.S. manufacturing projects, including those led by South Korean companies, requires far more skilled workers than current visa programs allow.

U.S. Homeland Security Secretary Kristi Noem defended the Georgia immigration raid on Monday as "a great opportunity" to ensure that foreign investors follow the Trump administration's immigration policy.

After the two top diplomats' meeting on Wednesday, Cho told South Korean reporters that the two sides have agreed to form a working group to address visa issues, including the creation of a new visa category that would better support South Korean business trips and operations in the United States. ■