WASHINGTON -- US sanctions on Iran will remain in place until Tehran returns to full compliance with the 2015 nuclear deal, a state department spokesperson said Tuesday, suggesting that there will be no immediate release of some $7 billion of Iranian assets frozen in South Korea.

On Tuesday (Seoul time), the South Korean foreign ministry said first vice minister, Choi Jong-kun, will visit Vienna for talks with negotiators from the US and five other member countries of the Iran nuclear deal, apparently to discuss a possible solution to the Iranian assets held in South Korean banks.

The countries are currently holding eighth round of negotiations with Iran in Vienna to discuss their mutual return to the nuclear deal, called the Joint Comprehensive Plan of Action (JCPOA). They include Britain, China, Russia, France, and Germany together with the European Union.

State department spokesperson, Ned Price, said sanctions relief was at the heart of the ongoing negotiations and that "nothing is agreed until everything is agreed."

"So I wouldn't want to get ahead of where we are," he added when asked about the US position on the Iranian assets frozen in South Korea in a telephonic press briefing.

About $7 billion worth of Iranian assets remain frozen in two South Korean banks under the US sanctions imposed following the US' withdrawal from the JCPOA in 2018. (Yonhap)