There is a palpable sense of anticipation in the business community ahead of the planned lifting of international sanctions against Iran in the coming months but also a number of concerns.

New opportunities for overseas companies will arise across all major sectors but will not come without challenges, not least in the legal complications of the sanctions remaining in place.

During discussions at MEED’s Opportunity Iran event on 29 September it was clear that potential investors view the continuation of some existing US sanctions as problematic to companies entering the Iranian market.

Only the US-enforced sanctions related to Iran’s nuclear activities will be lifted as a consequence of the Vienna deal but sanctions enacted by Congress in 1995 – related to human rights and support for terrorists – will remain in place. This means that US oil companies, banks and other firms will still be prohibited from doing business in Iran.

There are exceptions to the rule that US companies and individuals cannot do business in Iran. US aircraft manufacturers will be allowed to deal with Iran after Implementation Day – when the nuclear-related sanctions are lifted.

Boeing is reported to be planning a deal to sell civilian aircraft and parts to Iran that could amount to a value of $20bn over the next decade. At the same time, US food and pharmaceutical companies have always been exempt.

Investors are also concerned about the possibility of nuclear-related sanctions “snapping back” if Iran violates the terms of the Vienna agreement on its uranium enrichment programme.

The complications over remaining sanctions reinforce the need for companies to get detailed advice before navigating a path through the remaining sanctions to do business in Iran.