The European efforts to help Iranians benefit from the nuclear deal despite the US sanctions is "difficult but it's possible", said French Senator Philippe Bonnecarrere.

One way was "to have at least one Iranian bank remain connected to the international banking system through SWIFT to keep up commercial relations on goods or services that are not subject to sanctions," he added.

Bonnecarrere, who heads the France-Iran friendship group in the upper house of parliament, made the remarks during a news conference with French and Iranian counterparts.

The 2015 nuclear deal was agreed between Iran and the so-called 5+1 group -- UN Security Council permanent members Britain, China, France, Russia and the United States, plus Germany.

Bonnecarrere was in Iran with six other members of the French parliament.

The visit was a sign of "all the determination and all the will of France to keep alive the nuclear agreement," said Delphine O, one of lawmakers.