A French-Iranian citizen who left Iran in 2009 after facing espionage charges has been sentenced to six years in jail following her return to the country to visit her critically ill mother.

Nazak Afshar, 58, a former French embassy employee, was arrested last month on arrival at Tehran airport, the opposition website Kaleme reported on Sunday.

She was freed on bail from Evin prison after sentencing, it said. The Iranian judiciary has not commented on her case or made the charges against her public.

Afshar, who had dual citizenship, was arrested and tried in 2009 on charges of spying and acting against Iran’s national security. No verdict was issued and she was freed following the intervention of the French government, leaving the country the same year.

The potential opening up to the west after last year’s nuclear deal has alarmed Iranian hardliners, and Afshar’s arrest appears to be part of a crackdown against what some officials have portrayed as western infiltration.

Several other dual-nationality citizens or expatriates have been arrested on returning to visit Iran. A spokesman for the Iranian judiciary said on Sunday that four had recently been sentenced for their connections to foreign countries.

“Five people who were arrested recently for their connections outside the country were put on trial … and four of them have received their sentences,” Gholamhossein Mohseni Ejei was quoted as saying by the Tasnim news agency.

Iran does not recognise dual nationality.

Iranian conservative media reported last week that the presenter of a pro-opposition television channel was arrested as he travelled to Iran in “the disguise of visiting relatives”.

Sabri Hassanpour was host of the online network Simay-e Rahayi (Liberation TV) in the Netherlands and an outspoken critic of the Islamic Republic.

Other dual nationals Iran is holding include Iranian-Briton Kamal Foroughi, 76, who was arrested in 2011 while working in Tehran as a business consultant. Iranian-US citizens Siamak Namazi and his 80-year-old father, Baquer, are also in jail.

Iran’s judiciary spokesman said in January that most of the detained dual nationals were facing espionage charges.