Iran's envoy to nuclear deal talks in Vienna clashed with Tehran's state-owned Press TV on Tuesday, after he publicly questioned the veracity of its reporting.
Abbas Araghchi, who is Iran’s Deputy Foreign Minister, posted on social media on Tuesday night: “I don't know who the 'informed source' of Press TV in Vienna is, but s/he is certainly not 'informed'."
It was unclear to which report he was referring, with Press TV regularly quoting “informed sources”.
"Instead of questioning the credibility of Press TV's news sources, Mr Araghchi should have explicitly stated which information provided by Press TV news sources was distorted," Press TV responded on Twitter.
“We look forward to hearing from him.”
Press TV belongs to a state-owned organisation, the Islamic Republic of Iran Broadcasting, and its head is appointed by Iran's supreme leader, Ayatollah Ali Khamenei.
The talks in Vienna, which began in early April, aim to bring the US and Iran back into the 2015 nuclear deal that Tehran agreed to with world powers.
Negotiators on all sides say progress is being made although they concede there is still a long way ahead.
Mr Araghchi earlier said that after days “of intensive talks, it appears that we are now on the right track. But difficult way to go”.
US President Joe Biden wants to return to the accord, from which his predecessor Donald Trump withdrew in 2018, but only if Iran stops ramping up its nuclear activities.
Tehran says it is ready to return to compliance, but only if the US reverses the heavy sanctions that Mr Trump imposed on Iran when he withdrew from the deal.