Iran reportedly moved five U.S. nationals from prison to house arrest on Thursday in the first step of an emerging deal with Washington that would unfreeze Tehran's assets in South Korea and free several jailed Iranians.

A spokesperson for the White House's National Security Council(NSC) issued a statement that it has received confirmation that the five U.S. citizens who it said were unjustly detained have been placed under house arrest.

The five had been imprisoned in Evin Prison, one of the most notorious detention centers in Iran, on charges of spying.

The statement said that negotiations for their eventual release remain ongoing and are delicate, so few details will be available about the state of their house arrest or efforts to secure their freedom.

Quoting Iran's mission to the United Nations, the country’s state news agency IRNA reported that five Iranians would be released from U.S. prisons in exchange.

The deal between Iran and the U.S. reportedly includes permission for Iran to access its frozen assets in South Korea, Iraq and Europe.