Paris has decried Iran sentencing a French national to five years in prison on a baseless conviction, calling for his release and three other of its nationals held by Tehran.

"We learned with the greatest concern that Mr. Louis Arnaud had been sentenced to five years in prison," Foreign Ministry spokesperson Anne-Claire Legendre said in a statement.

"This conviction, for which there is nothing to support and the absence of any access to a lawyer, is unacceptable."

Ties between France and Iran have been strained over the issue in what Paris has said are arbitrary arrests that are equivalent to state hostage taking.

Arnaud, who has been held since September 2022, is one of four French nationals held in Iran, and is being detained at the Evin prison in Tehran.

His mother, Sylvie, told Reuters the pretext given for his sentencing were for "propaganda and harming the security of the Iranian state."

"These are completely baseless and a carbon copy of what they attribute to other Europeans held in Iran," she said.

In recent years, Iran's elite Revolutionary Guards have arrested dozens of dual nationals and foreigners, mostly on charges related to espionage and security.

Rights groups have accused Iran of trying to extract concessions from other countries through such arrests. Iran, which does not recognize dual nationality, denies taking prisoners to gain diplomatic leverage.

(Report by Reuters)