South Korean Prime Minister Chung Sye-kyun arrived in Iran on Sunday to hold talks over the 2015 nuclear deal between Iran and world powers, Seoul officials said.
Chung is the first South Korean prime minister to visit Iran in 44 years amid icy relations between the two countries due to Iran's military cooperation with North Korea.
Tension rose after Iran seized a South Korean ship and its sailors in the Strait of Hormuz in January, accusing them of polluting the waters, and demanded South Korea release $7 billion in assets frozen in South Korean banks under US sanctions.
Chung's trip comes days after Iran released the tanker and its captain, the last member of its 20-strong crew, with South Korea vowing to help secure the release of the funds.
Iran and world powers held talks last week aimed at reviving the 2015 nuclear deal that former US President Donald Trump abandoned three years ago.
After talks on Sunday with Iranian First Vice President Eshaq Jahangiri, Chung displayed his willingness to support efforts to revive the deal, aimed at preventing Tehran from acquiring nuclear weapons, formally named the Joint Comprehensive Plan of Action (JCPOA), according to Iranian and South Korean media reports, Reuters reported.
A return to the JCPOA would help improve relations between Seoul and Tehran, Chung said, pledging to step up cooperation with Washington and other countries over the Iranian funds.
The Biden administration is trying to find a way to rejoin the accord and lift the sanctions at talks in Vienna with Iran, mediated by European signatories.
Seoul officials have said they only can release the Iranian billions with a nod from Washington.