WASHINGTON (Reuters) - The United States on Thursday granted a license to allow for certain humanitarian trade transactions with Iran’s sanctioned central bank, a move it said was in step with the formalization of a Swiss humanitarian aid channel.

The newly created channel, which the U.S. Treasury Department said became fully operational on Thursday as it granted the license, would allow for companies to send food, medicine and other critical supplies to Iran.

Last week, U.S. Special Representative for Iran Brian Hook said there was a lot of interest from food and drug companies in using the Swiss Humanitarian Trade Arrangement, which began trial operations last month with shipments of medicine.

The SHTA seeks to ensure that Swiss-based exporters and trading companies in the food, pharmaceutical and medical sectors have a secure payment channel with a Swiss bank, through which payments for their exports to Iran are guaranteed.

Food, medicine and other humanitarian supplies are exempt from the sanctions that Washington reimposed on Tehran after President Donald Trump walked away from a 2015 international deal over Iran’s nuclear program.

But the U.S. measures targeting everything from oil sales to shipping and financial activities have deterred several foreign banks from doing business with the Islamic Republic - including humanitarian deals.