ZURICH — Since a landmark nuclear deal went into effect in January, US officials have conducted roundtables with banking officials in more than 15 countries, but failed to reassure major foreign banks that it is OK for them to return to Iran, Al-Monitor has learned.

A business source briefed on the issue told Al-Monitor at a May 3-4 business conference in Zurich on condition of anonymity that two Swiss banks — Credit Suisse and UBS — were among those approached by officials from the US Department of State and the US Treasury. Most big foreign banks have so far rejected a return to Iran for a host of reasons, including heavy fines paid to the US government for past sanctions violations and concerns that the sanctions environment could change again for the worse.

Gregg Rosenberg, a spokesman for UBS, told Al-Monitor that his bank was not going to handle Iran business. “At this time there are no changes to our global sanctions policy, which restricts business activity with or involving Iran, including client activity such as payments or trading that involves Iran," Rosenberg said in an email.

A Credit Suisse spokeswoman had a similar reply: “As a global bank Credit Suisse complies with various national and international sanctions programs. While the international community has recently lifted a part of the sanctions against Iran, other Iran sanctions that impact our Bank’s international operations remain in place. Credit Suisse maintains its general policy to abstain from conducting business with or involving Iran. We continue to closely monitor the situation.”