Iran's foreign minister Friday threw the ball back into the US president's court over Tehran's nuclear agreement with foreign powers, after the two countries carried out a prisoner swap.

President Donald Trump had voiced hope for progress with Iran a day earlier, after the Islamic republic released a US Navy veteran and the United States freed two Iranians. "Thank you to Iran, it shows a deal is possible!" Trump had tweeted.

Foreign Minister Mohammad Javad Zarif responded to Trump on Twitter Friday, saying, "We achieved humanitarian swap *despite* your subordinates' efforts". "And we had a deal when you entered office. Iran & other JCPOA participants never left the table", he said, using an acronym for a landmark 2015 nuclear deal.

The multilateral accord, known formally as the Joint Comprehensive Plan of Action, gave the Islamic republic relief from international sanctions in return for limits on its nuclear programme. Tensions between Tehran and Washington escalated in 2018 after Trump unilaterally withdrew the US from the agreement and reimposed crippling sanctions on Iran.

The other partners to the accord are Britain, China, France, Germany and Russia. "Your advisors — most fired by now — made a dumb bet. Up to you to decide *when* you want to fix it," Zarif added.

US Navy veteran Michael White was arrested in July 2018 in Iran's northeastern city of Mashhad after visiting a woman whom he had reportedly met online. As he was flying home Thursday, a US federal judge issued an order to free an Iranian-American doctor, Majid Taheri.

A day earlier, a prominent Iranian scientist arrested in 2016 returned to Iran, but both the arch-rival nations denied that was a swap. Trump has pursued a "maximum pressure" campaign against Tehran, imposing sweeping sanctions and in January ordering a drone strike that killed a top Iranian general.