SEOUL, Sept. 12 (UPI) — South Korean Foreign Minister Cho Hyun called on Washington on Friday to reform its visa policies to avoid a repeat of last week’s immigration raid and detention of South Korean workers at a Hyundai electric battery plant in Georgia.

Cho met U.S. Sens. Todd Young, Bill Hagerty and Andy Kim in Washington on Wednesday and Thursday to express the South Korean public’s “deep concern” over the arrests of its professionals, the ministry said in a statement.

Multiple agencies led by U.S. Immigration and Customs Enforcement arrested 475 people, most of whom are South Korean nationals, at a Hyundai-LG Energy Solutions battery plant near Savannah, Ga., on Sep. 4.

After being held for a week, 316 South Koreans and 14 other employees were released and departed from Atlanta on a charter jet late Thursday morning local time.

The plane landed at Incheon International Airport near Seoul at around 3:23 p.m. on Friday, news agency Yonhap reported.

In his meeting with the senators, Cho “emphasized the urgent need for fundamental measures to prevent recurrence of such incidents and to protect our workforce from unfair treatment so that Korean companies can fulfill their investment commitments in the United States,” the ministry said.

He urged Congress to support visa reform, including the introduction of a new visa category for South Korean professionals on investment projects.

The senators “agreed that this incident should not negatively impact economic cooperation between South Korea and the United States,” according to the ministry.

“They welcomed the agreement between the two countries to explore long-term solutions, including the establishment of a South Korea-U.S. working group, to prevent similar incidents,” the ministry said. “They also pledged to explore necessary institutional support, including legislative action.”

On Thursday, South Korean President Lee Jae Myung called the immigration raid “perplexing” and said it could deter firms from making future investments in the United States. Lee touched on the subject during a press conference marking his 100th day in office, noting that South Korean firms regularly send skilled workers for short stays to help establish overseas factories.

The roundup came less than two weeks after Lee met with Trump in the White House, and has sparked widespread public shock and anger in South Korea. Seoul and Washington are looking to finalize a trade deal struck in July that includes a $350 billion investment pledge by South Korea.

Without visa reform, companies “will have to worry about whether establishing a local factory in the United States will be subject to all sorts of disadvantages or difficulties,” Lee said.

“Under the current circumstances, Korean companies will be very hesitant to make direct investments in the United States,” he said.