When Parviz Aghili returned to his native Iran to become an entrepreneur, he had to give up the lifestyle of first-class flights and five-star hotels that went with his role as an expatriate executive. He has no regrets. “I have never felt I made a mistake by coming back. I never let any doubts cross my mind,” he says.

A downgraded lifestyle was not the only problem facing the 60-year-old founder of Karafarin, the first private-sector bank to begin operating in Iran since the 1979 revolution. Western countries last year imposed banking sanctions in a bid to clamp down on Iran’s nuclear ambitions and the populist policies of President Mahmoud Ahmadi-Nejad.