A US lawmaker has called it outrageous that Iran detained European nationals while European Union’s coordinator of nuclear talks Enrique Mora is in Tehran to make a deal.

“This should be the final nail in the coffin for any bad deal with Iran”, Idaho’s Republican Senator Jim Risch, who is a ranking member at the foreign relations committee, said in tweet on Wednesday.

Mora met with Tehran’s chief negotiator Ali Bagheri-Kani on Wednesday as Iran’s Intelligence Ministry announced it arrested two European citizens.

The two European nationals arrested in Iran were identified as Cécile Kohler, the head of the biggest federations of teachers' unions in France and her husband.

“The EU must accept that Iran is not a trustworthy interlocutor given its continued aggression”, Risch added.

Before departing for Tehran on Tuesday, he tweeted that he would be discussing both the revival of the nuclear talks and “other issues”, prompting speculations that the visit could be as much about prisoner swap deals between Europe and Tehran as to find a common ground to jump start the JCPOA talks stalled since mid-March.

Iran has been threatening Sweden for the long trial of a former judicial official who was arrested in Stockholm for his alleged role in the killing of thousands of political prisoners in Iran in 1988. There is also the case of a former Iranian diplomat who is serving a 20-year prison term in Belgium for organizing a plot to bomb an opposition rally in France. Iran also demands his release.

On Tuesday Tehran ruled out any prisoner exchange with Europe as it says it will execute Hamidreza Djalali, a Swedish Iranian dual citizen, who was arrested in 2016 on a visit to an Iranian university and convicted on alleged “espionage for Israel.”