It could have been an oil fair anywhere in the world. In the huge pavilions there were flashy displays for Shell, Lukoil, Siemens and Statoil. And all were jumping at the chance to show off their products and services to potential customers.

But this was not just anywhere. It was in Tehran, at a five-day oil trade fair that has attracted 450 international companies, the largest contingents coming from Germany, the UK, Russia and China.