Iran's permanent representative to the United Nations has denied a media report concerning a prisoner swap agreement between Iran and the United States, the official IRNA news agency reported on Monday.

"This news is not confirmed," Majid Takht Ravanchi, the representative, told IRNA.

Iran has always emphasized the comprehensive exchange of prisoners with the U.S., Takht Ravanchi told IRNA. 

The U.S. earlier on Sunday had also denied a report by Iran's state television that the arch-foes had reached a prisoner swap deal in exchange for the release of $7 billion in frozen Iranian oil funds under U.S. sanctions in other countries. 

Iranian state television said on Sunday that Tehran would free four Americans accused of spying in exchange for four Iranians held in the U.S. and the release of the frozen Iranian funds. 

"Release of Nazanin Zaghari in exchange for UK's payment of its 400 million pound debt to Iran has also been finalized. The source also said the Biden administration has agreed to pay Iran $7 billion," it said. 

The U.S. government denied that an agreement has been reached. U.S. Department of State Spokesman Ned Price said reports of a prisoner swap deal "are not true."

White House Chief of Staff Ron Klain also denied the report.

"Unfortunately, that report is untrue. There is no agreement to release these four Americans," Klain said on CBS' "Face the Nation." 

U.S. officials regularly raise the issue of detained Americans with Iran, Klain said. 

Iran's envoy to the UN Majid Takht Ravanchi said the report could not be confirmed, adding that Tehran has always called for a full prisoner exchange with Washington. 

Despite U.S. denial, The Associated Press reported that although no formal proposal for a swap has yet been presented to officials in Washington, let alone been signed off on by the White House, the specificity of the reports from Iran suggested that working-level consideration of a deal is at least underway. 

Parties to the Joint Comprehensive Plan of Action, also known as the Iran nuclear deal, are holding talks in Vienna, Austria, to revive the accord, which Washington abandoned three years ago while reimposing sanctions on Tehran. 

After Saturday's latest round of talks, diplomats said progress has been made but they still need more work and time to bring about a future agreement. 

A U.S. delegation in Vienna is also taking part in indirect talks with Iran, with diplomats from the other world powers acting as go-betweens. 

Iran said $20 billion of its oil revenue has been frozen in some foreign countries under U.S. sanctions since 2018. 

UK plays it down 

Iranian state TV, quoting an unidentified Iranian official, also said British-Iranian national Nazanin Zaghari-Ratcliffe would be released once Britain had paid off a debt on military equipment owed to Tehran. 

British officials played down the report. The British Foreign Office later in a statement responded that "legal discussions are ongoing" over the debt, saying it will not make further comment on the issue. 

The dispute over the UK's debt dates back to the 1970s when the then-shah of Iran paid $550 million for army tanks. Britain refused to deliver the tanks to the new Islamic Republic when the shah was ousted in the 1979 revolution. 

UK Foreign Secretary Dominic Raab Sunday said that London recognized that the debt should be repaid, adding that "we're looking at arrangements for securing that." 

(With input from agencies)

(Cover: An Iranian national flag flutters in front of the International Atomic Energy Agency (IAEA) headquarters in Vienna, Austria, September 9, 2019. /Reuters)