Five Americans moved to house arrest will be allowed to leave Iran after $6 billion of Iranian funds in South Korea are unfrozen, a source told Reuters Thursday, adding that under a deal reached between Tehran and Washington several jailed Iranians will be released.

The source briefed on the deal said "minor technical issues regarding the transfer of the funds to a Persian Gulf country is being discussed by the parties involved in the deal."

The U.S. has confirmed that five detained Americans remain on house arrest and negotiations for their eventual release remain ongoing, a National Security Council spokesperson.

The move comes amid months of heightened tensions between Iran and the U.S.

A major American military buildup in the Persian Gulf is underway, with the possibility of armed U.S. troops boarding and guarding commercial ships traveling through the crucial Strait of Hormuz, through which 20% of all oil traded passes.

Iran in past months has overstated progress in talks, likely conducted with mediation from Oman and Qatar, on a potential trade.

The U.S. in March called remarks by Iranian Foreign Minister Hossein Amirabdollahian that a deal for a swap was close a “cruel lie.”

U.S.-based lawyer Jared Genser identified three of the prisoners as Siamak Namazi, Emad Shargi, and Morad Tahbaz. Genser did not identify the fourth and fifth prisoners.

Material from Reuters and The Associated Press was used in compiling this report.