LONDON (Reuters) - Iranian authorities sentenced a member of Iran’s nuclear negotiating team to five years in jail, Tasnim news agency reported on Wednesday although it gave no details of the case.

Iran reached a nuclear deal with the United States and five other major powers in 2015 that led to the lifting of most of the international sanctions against Iran in return for curbs on its nuclear program.

The potential detente with the West has alarmed Iranian hardliners, who have seen a flood of European trade and investment delegations arrive in Tehran to discuss possible deals, according to Iran experts.

Reports last year in the Iranian media said a nuclear negotiator with dual nationality had been arrested after being accused of providing sensitive economic information to Iran’s enemies.

In May, the judiciary spokesman Gholamhossein Mohseni Ejei said a member of the negotiating team who was facing espionage charges had been sentenced to a prison term, but added that he could not provide details since the verdict could be appealed.

“The case was reviewed in an appeal court and a five-year jail sentence was upheld,” Tasnim quoted an “informed source” as saying on Wednesday but did not name the person.

Tasnim reported in July 2016 that a member of the negotiating team who was in charge of banking affairs during the talks had been arrested.

The agency and some other semi-official media named him as Abdolrasul Dori Esfahani with Iranian-Canadian nationality and possibly holding other passports.

Security officials have arrested several businessmen, including Iranians holding joint American, European or Canadian citizenship, as part of a crackdown on “Western infiltration”.

Iran’s Islamic Revolutionary Guard Corps in October 2015 detained Siamak Namazi, a businessman in his mid-40s with dual U.S.-Iranian citizenship, while he was visiting family in Tehran. The IRGC in February arrested his 80-year-old father, Baquer Namazi, a former Iranian provincial governor and former UNICEF official who also has dual citizenship.

Both men were jailed in 2016 for 10 years for spying and cooperating with the U.S. government.