Iranian President Hassan Rouhani speaks at a press conference in Tehran, Iran, on Oct. 14, 2019. (Xinhua/Ahmad Halabisaz)

The US and Iran clashed Monday on the prospect of a prisoner swap, with a US official mockingly urging the adversary to send a plane to repatriate its citizens.

An Iranian government spokesman said Sunday that Tehran had offered "some time ago" to exchange all Iranian and American prisoners but was waiting for a response from the US.

He received a reply of sorts Monday via social media as Ken Cuccinelli, Acting Deputy Homeland Security Secretary, insisted that the US had been trying to send back Iranian nationals.

"We have 11 of your citizens who are illegal aliens who we have been trying to return to your country," tweeted Cuccinelli, who is known for his hardline views against immigration.

"You suddenly SAY you want them back, so how about you send a charter plane over and we'll return all 11 at once?" he wrote, attacking the credibility of Iranian Foreign Minister Mohammad Javad Zarif.

Iranian Foreign Ministry Spokesman Abbas Mousavi hit back on Twitter, noting that Zarif has been publicly proposing a prisoner swap since September 2018, and told Cuccinelli: "Stop talking rubbish!"

"Your regime has reacted callously and risked their lives. (The world) is watching your actions, not your words. Let our citizens go!" Mousavi said in the tweet.

Cuccinelli stated that the US has been trying to send back Sirous Asgari, an Iranian scientist acquitted in November on US charges that he stole state secrets while on an academic visit to Ohio.

The Iranian Foreign Ministry said that Asgari contracted COVID-19 while in US custody.

AFP