US President Joe Biden's mentioning of South Korea in his State of the Union address showed his gratitude for Seoul's joining of sanctions on Russia's invasion of Ukraine, a senior official at Cheong Wa Dae said Monday.

In his first State of the Union address last week, Biden thanked South Korea, along with dozens of other countries, for condemning what he called Russia's "unjustified" and "totally unprovoked" aggression on Ukraine.

US officials have since informed the South that Biden mentioned South Korea to express his gratitude for joining sanctions on Russia, said Park Soo-hyun, senior presidential secretary for public communication, on a TBS radio.

Park rejected criticism that South Korea's lukewarm attitude about sanctions on Moscow led to the country's belated exemption from the expanded US export restrictions on Russia, saying the government had to revise related regulations due to differences in export control systems.

Last month, the US government announced the Foreign Direct Product Rule (FDPR) for all of Russia as part of its export controls to block Russia's access to global high-tech products and other foreign-produced major items, such as semiconductors, over the Russian invasion of Ukraine.

The measure calls on companies to receive a license from the US for tech-related items using US technology before they can be shipped to Russia, which is feared to affect major South Korean exporters, as they use US technology and software.

South Korea had been originally excluded from a list of nations that were exempted from the FDPR rule but won an exemption last week after negotiations with the US government. (Yonhap)