The world's top insulin maker, Novo Nordisk, said on Tuesday it would build a 70 million euro ($78 million) facility in Iran, signalling its "long-term commitment" to the country.

"We are happy to commit to this manufacturing facility in Iran," Ole Moelskov Bech, who heads part of the group's Middle East business, said in a statement.

"It signals our long-term commitment to Iran, a country where close to five million people have diabetes," he added.

The Danish company said the manufacturing plant would produce its FlexPen insulin pens and that it would take five years to complete.

Medication is exempt from the sanctions aimed at preventing Iran from gaining a nuclear weapon, and Novo Nordisk has sold its products in the country through a subsidiary since 2005.

However, restrictions on banking and technology have made conducting business in Iran harder for the company.

"There are prospects for significant growth in Iran's economy, and that also means you can better afford investing in healthcare," Bech told Danish news agency Ritzau.

The nuclear deal between Iran and Britain, China, France, Germany, Russia and the United States aims to curb Tehran's nuclear drive in exchange for a gradual lifting of sanctions imposed on its economy since 2006.

The lifting of sanctions, expected from 2016, is expected to return much-awaited foreign investment to Iran, a country rich with oil and gas resources and a population of almost 80 million.

France opened a business development office in Tehran on Monday seeking to renew once-strong economic ties with Iran after the July 14 nuclear deal in the face of what it said was "fierce competition" from other European and American firms.