The US department has not explained why South Korea was added to the list last week. An inclusion curb cooperation, though a DOE spokesperson said Seoul faced no new limits on bilateral cooperation in science and technology from the designation.

Seoul’s foreign ministry said the US decision was understood to have been due to “security-related matters” linked to a research centre affiliated with the DOE.

It was not due to South Korea’s foreign policy, the ministry said in a statement, adding it had contacted US counterparts.

The US cited cases of South Korean researchers breaching security rules during work trips and joint projects with DOE-affiliated research centres, the Yonhap news agency reported.

Acting President Choi Sang-mok said efforts should be made to avoid negative impacts on cooperation and called for the industry minister to meet with the US secretary of energy this week, according to a statement from the finance ministry after a meeting on foreign economic issues.

Politicians in Seoul have traded blame over the sensitive country designation.

Lee Jae-myung, leader of the opposition Democratic Party, criticised the government, calling the US move a “perfect diplomatic failure”.

Ruling party lawmaker Kwon Young-se accused the Democratic Party which controls parliament of pushing anti-US sentiment and excessively impeaching government officials including President Yoon Suk Yeol, a move that Kwon said was the biggest cause of the sensitive country designation.

According to the DOE’s website, countries may appear on the sensitive country list for reasons such as national security, nuclear non-proliferation, regional instability, threats to national economic security or terrorism support.