NEW YORK: US Secretary of State Antony Blinken said Monday that he spoke to five US citizens freed from Iran after they landed in Qatar in a swap.

"It's very good to be able to say that our fellow citizens are free," Blinken told reporters in New York.

"I can tell you that it was for them, for me, an emotional conversation."

President Joe Biden approved the swap despite Republican criticism. As part of the deal, South Korea shifted $6 billion in frozen Iranian funds to an account in Doha that US officials say is restricted to humanitarian use.

US allows $6bn transfer as part of Iran prisoner swap

"President Biden has demonstrated that he's prepared to make tough and difficult decisions," Blinken said.

"I have no higher priority. The president has no higher priority than making sure that Americans who are unjustly detained anywhere can come home and we will continue that work."

Blinken said that the prisoner swap was a "different track" from other issues with Iran such as its contested nuclear program.

"We've been focused on working independently to bring these Americans home, so it doesn't speak to anything else in the relationship," he said.